How successful have such tax deferred plans been at their original intention of providing ordinary Americans with a secure retirement?

These numbers (from 2017) would suggest not very successful. If all retirees have to go with this is SS (no pension or employer provided health insurance), it would be tough living another 20-30 years on those amounts - even if savvy investors and even if the current exuberant market were to continue bubbling along.
Remember that these are tax deferred amounts - meaning a chunk of these savings will go to covering the deferred taxes upon withdrawal.
2017 Average 401K Retirement Plan Totals
Under age 25
Average 401(k) account balance: $4,773
Average 401(k) savings rate: 4.8 percent
Age 25 to 34
Average 401(k) account balance: $24,728
Average 401(k) savings rate: 5.9 percent
Age 35 to 44
Average 401(k) account balance: $68,935
Average 401(k) savings rate: 6.3 percent
Age 45 to 54
Average 401(k) account balance: $129,051
Average 401(k) savings rate: 7 percent
Age 55 to 64
Average 401(k) account balance: $190,505
Average 401(k) savings rate: 8.3 percent
Age 65 plus
Average 401(k) account balance: $209,984
Average 401(k) savings rate: 9 percent
https://money.usnews.com/money/retirement/401ks/articles/2018-07-23/are-your-retirement-savings-ahead-of-the-curve
Above numbers based on a survey of actual 401K plan participants. Considering that fewer than half of all U.S. workers participate in a 401K plan (for a variety of reasons) the picture looks even bleaker.
https://www.fool.com/retirement/2017/06/19/does-the-average-american-have-a-401k.aspx

Mandatory withdrawals from an IRA do not mandate spending. The money that is withdrawn, less taxes, can compound in a taxable account forever. It will even get a step up in basis at death, which doesn't happen in an IRA.
I do though have a real concern with "forever". This is how wealth concentrates within families. I see no public interest in that. Nor is there a self-evident right to direct where your money goes after death. As Blackstone wrote:

Naturally speaking, the instant a man ceases to be, he ceases to have any dominion: else if he had a right to dispose of his acquisitions one moment beyond his life he would also have a right to direct their disposal for a million of ages after him . which would be highly absurd and inconvenient. All property must, therefore, cease upon death, considering men as absolute individuals unconnected with civil society. . . . Wills, therefore, and testaments, rights of inheritance and succession, are all of them creatures of the civil or municipal laws

https://www.jstor.org/stable/25102211

These are not very early estimates of the annual distributions, but of Sept. distributions. Some Fidelity funds typically distribute gains in Sept and again in December.
It seems that in addition to HAINX, we have a couple more examples of what can happen when a new manager (even from the same management company) takes over a fund and turns its portfolio upside down. (I thought Fidelity was trying to get away from that.)
FDGFX - 14.75% distribution - M* writes "Gordon Scott officially took over in January 2018"
FCPVX - 18.82% distribution - M* writes: "The fund has undergone two manager transitions in recent years."

Suppose there were a cap, where all amounts greater than the cap had to be withdrawn:
Age 71: $1,000,000
Age 72: $ 970,000
Age 73: $ 940,000
...
Age 81: $ 700,000
...
Age 91: $ 400,000
...
Age 101:$ 100,000
Age 102:$ 80,000
Age 103:$ 60,000
Age 104:$ 40,000
Age 105:$ 20,000
How would this gradually reduced cap impede those who started saving late? ISTM that they're the ones who would benefit, since they would have the smaller accounts and thus be allowed to let their IRAs grow.
Perhaps you had something different in mind for how a cap (even a fixed limit cap) would work?

IMHO, the suggested rationale that RMDs be eliminated (or at least pushed back a few years, say, to age 75) because some people (a) are working now so don't need the money (b) will need the benefit of longer tax deferrals on those few years of RMDs they take before they retire, is a red herring.
If that really is a problem, it can be easily addressed without making broad changes in RMDs that affect everyone.
To some extent, it is already addressed. If someone over 70 works for an employer that offers a retirement plan accepting rollovers, the worker need just transfer the IRAs into the retirement plan. That gets rid of any RMD so long as the person continues working for the employer.
"The vast majority would still need to withdraw money on a regular cadence but allowing the untapped portion to further compound." Those workers in this "vast majority" withdraw money (RMDs or more) on a regular cadence and leave the rest of the IRA untapped to further compound. Done! That's the way things work now.
For the few (the "unvast minority"?) who don't need any money while working, they pay their taxes on the modest annual RMDs ("tax a little now") for a few years while they continue to work. They're not required to spend those RMDs. So they move their RMDs to taxable accounts, where they "benefit from additional time for their investments to compound"
There's no need to create more opportunities to abuse the system, merely to address what is to a large extent (i.e. for the "vast majority") not a problem. And for the few who are substantially affected, there are more targeted ways of helping them.

@DavidrMoran. Hey,,,,, it's a subject that is on my mind right now. I will be turning 70.5 next year,,,, I was pointing up his hypocrisy... I also understand that the elite don't need the money and would be happy to let it grow tax deferred. Regular folks will need the money and it might be taxable,,, particularly if husband and wife are of a certain age.

I was just going to ask LB how he thinks tax-deferred savings should be handled, and the 5y window sounds like a good idea.
I wonder if there is a progressive case to be made for handling Roths differently, as there is and has been for the new SaLT-deduction caps.

"the prosperity was strongly skewed in favor of the earnings of business and the incomes of the rich. In consequence, continued prosperity depended on continuing high investment expenditures by business, continuing high consumer expenditures by the affluent.
As share volumes came rushing down, prudence in all investment decisions rose as a reciprocal. Solid enterprises began to reconsider their investment commitments. Banks were suddenly cautious. Borrowers had been caught in the market. Better to have plenty of cash. And individual investors, their fingers badly scorched, were also poor prospects for the new issues of securities.
The blight on consumer expenditures was equally severe. Those who had been spending capital gains no longer had them. Many not directly affected thought it prudent to behave as though they had been."
John Kenneth Galbraith: Money, Whence It Came, Where It Went
(Houghton Mifflin Company, Boston, 1975, pg 184).
[Lightly edited for brevity and to accent relevance to the present time.]

In 2011 the English government (using data from England and Wales) conducted a study to estimate the probability of an individual 50 years old in 2011 to reach 100 years of age. The results were 11.4% for males and 17.0% for females. These numbers if applied to the US, would imply that we might be significantly underestimating the income requirements during retirement.
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/223114/diffs_life_expectancy_20_50_80.pdf

Normally when I see these tables, I just go ooohh, look at the pretty pictures.
But when there's coloring outside the lines, I take a closer look. The S&P 500 sector performance table shows eleven rows of sectors (plus a row for the S&P 500). The problem is that until 2016 there were only ten sectors.
This is how the chart looked through 2015.
http://www.usfunds.com/media/files/pdfs/researchreports/2016/Periodic-Table-of-Sector-Returns-2016.pdf

Here's State Street Global Advisors (SPDRs) current chart, with 10 sectors through 2015, and eleven sectors since.
http://www.sectorspdr.com/sectorspdr/Pdf/All Funds Documents/Document Resources/10 Year Sector Returns

I don't know where NovelInvestor got its figures or how it retrofitted the new Real Estate sector into earlier years. That should have been easy to do - Real Estate was simply carved out of Financials, so the other sectors' figures for the past decade should not have been changed. But looking at the NovelInvestor table, it seems they were.
https://www.reit.com/investing/investor-resources/gics-classification-real-estate
Just wait until the latest sector reorg hits these tables. With IT being split, Media being expanded, and other companies being moved around, it will be difficult to extend these new sectors back in time to create a "virtual" table of how these sectors might have done over the past ten years. (That's because there's ambiguity in how each of the companies would have been classified over the past decade as their businesses matured.)

@hank: My suggestion would be, take that 7.5% and put it into something that working for the remainder of 08. You said it yourself, "Still hoping for a change in direction. (Hope is not a viable investment plan.)" Believe me that's not going to happen, and you won't miss the four funds you mentioned.
Regards,
Ted

I don’t normally post buys / sells. But FWIW, over past 6 months I’ve nibbled on some of the real asset type funds I already owned as things got cheaper. Today, I find myself a bit overweight in that area - and yet it still hasn’t paid me back. The entire area is still in the doldrums.
Still hoping for a change in direction. (Hope is not a viable investment plan.) :)
Unlike @Ted, my point here is that when you buy things that look cheap ... they might get even cheaper. Here’s the 4 funds I’m referencing: PRAFX, TRREX, OPGSX, OQGAX. Together, they comprise 7.5% of total investments.

FYI: While the ever-climbing U.S. stock market (and the bubble forming in it) has been stealing most of the investing public's attention, a dangerous bubble has been forming under-the-radar in the corporate bond market. Interestingly, this corporate bond bubble is one of the main reasons why the stock market has been consistently pushing to new highs, and it will also eventually prove to be its undoing. In this report, I will show a variety of different charts to help explain the U.S. corporate bond bubble and the risk it poses to the stock market and economy.
Regards,
Ted
https://www.forbes.com/sites/jessecolombo/2018/08/29/the-u-s-is-experiencing-a-dangerous-corporate-debt-bubble/#2a2d9584600e

FYI: A presidential executive order that could lead to investors keeping their money longer in tax-deferred retirement accounts? What’s not for investment advisors to like?
Especially intriguing to advisors is the language in President Trump’s new executive order calling on the Treasury Department to review its rules for required mandatory withdrawals from 401(k)
Regards,
Ted
https://www.fa-mag.com/news/trump-calls-for-review-of-rule-requiring-rmds-at-70-1-2-40625.html?print

Totally agree that health care will consumer much larger part of our retirement resources. We still have over 15 years fom retirement. In the meantime, we maintain an active lifestyle, routine exercising (swimming and walking), and eating healthy.

@MFO Members: Bought PRHSX on 8/27/18, fund was up 2.87% for the week. During the same period of time the S&P 500 returned .98%. I know its only five days, but this is a perfect example by being aggressive you get enhanced returns.
Regards,
Ted :)

Looking at the new comms services sector, 50% is Google and Facebook, based on market cap FIFTY. That just reinforces my sense that market-cap weightings are a farce and lead to skewed index performance ... and why I don't invest according to indices or market caps myself.

My thoughts and positioning follow. As we open September Old_Skeet is currently just watching the markets and has been building my cash position since late June as my market barometer indicated that the S&P 500 Index moved from being undervalued in June to being fairly valued for most of July and August and just recently moved into overvalued status. I'm thinking with the upcoming November elections this will provide me a buying opportunity should I want to increase my equity allocation or perhaps open and build a fall spiff position as I'm thinking stocks will go soft around election time. Currently, my most recent Xray of my portfolio bubbled my asset allocation at 17% cash, 34% US equity, 18% foreign equity, 25% bonds and 6% other assets. During the past rolling quarter (90 day period) my commodity strategy fund (PCLAX, -3.2%) along with my emerging market fund (NEWFX, -3.5%) went soft while my aggressive growth fund (AOFAX, +19.6%) ... a dividend strategy fund (FDSAX, +7.7%) ... and, a large cap growth fund SPECX, +7.6%) all had a nice upward movement. Overall, I made some good money during this past rolling quarter.
So, for now, I just sit and await a good stock market pullback so I can put some cash to work (most likely in a spiff position) when the next buying opportunity presents itself as measured by my market barometer.
In closing ... I guess, for now, I ponder as I am not buying, nor selling, while I continue to build cash awaiting a good stock market pullback.

This is why ETFs like ProShares Ex-Tech (SPXT) will be picking up these stocks. My comment there:
https://www.mutualfundobserver.com/discuss/discussion/comment/105938/#Comment_105938
The point is that these firms don't just "dominate our digital lives", they dominate our lives. The value is in what they do (application), often more than in how they do it (technology).

FYI: ( Make sure your watch the video, its very well done, along with the Sidebar "Tech Stocks Could Be Winners in Big Sector Shift.)
Tech Stocks Could Be Winners in Big Sector Shif.)
A Market Shakeup Is Pushing Alphabet and Facebook Out of the Tech Sector
Photo: Javier Jaén
Think of Big Tech and companies like Alphabet, Amazon, Apple, and Facebook come to mind. The firms dominate our digital lives, living on our cellphones and influencing how we interact with people, buy things, get to places, access information, and consume entertainment. Their market impact has also been huge: These four stocks have returned 33.7% annually over the past five years, on average, versus the S&P 500’s 14.5%.
Regards,
Ted
https://www.barrons.com/articles/a-market-shakeup-is-pushing-alphabet-and-facebook-out-of-the-tech-sector-1535762710