Re: So…
PBGC coverage comes with a lot of strings attached as far as how the pension is managed, permitted types of investments, etc. If such coverage was offered for 401K/IRA plans but came with the same strings I'm sure a lot of people would loudly complain "it's my money I should be able to invest it however I want!"
If you want the freedom to put your retirement into bitcoin or use that account to buy options, it should be on you to deal with the consequence of that decision.
By contrast if you have a pension you have zero control over how the money is invested, so it shouldn't be your loss if bad investments are made with your money.
Maybe laws could be changed to allow some sort of pension-like scheme that money could be permanently transferred into from an IRA or 401K, with strictly limited returns in exchange for a similar PBGC-like safety net. But they don't need to be because the option already exists - using your IRA or 401K funds to buy an annuity that begins paying out at retirement age.