Why, do I tend to run on? :^)
does your suggestion involve some monitoring, regulating, and administering of these IRAs? Does it include a plan for those whose investments go sour? If your answer is "no" to all of these questions, my characterization of your position, above, is accurate. If your answer is "yes" to all these issues, then you are introducing a gigantic, complex, far more intrusive, new "Big Government" program to replace SS and THAT DOES NOT SERVE THE SAME PURPOSE.
Of course we need some sort of guidelines as far as appropriate investments. Low cost indexes which blend the Wilshire 5000 with a government bond component would be swell. As people get closer to retirement their bond portion would be increased and the stock would be decreased.
I don't see the government telling you how to safely invest your money is nearly as intrusive as them taking all your money with a promise that (wink-wink) it'll be here when you need it.
Apparently, you would not be satisfied to change the investment of the surplus to reflect your investment preferences while keeping the structure and goals of SS in tact. How, then, will your system be enforced? What about people who don't make enough to fund their retirement?(Your assumption that everyone will manage to earn sufficient returns is naive). The entire monetary system has blown up in Russia, Malaysia, Thailand, Argentina, and Brazil, but I guess you believe it can't happen here.
What if, they will need your employer's contribution plus half of your contribution for the next 40 years before they can start lowering it? Do you still favor the program? How about if it requires 3/4 of your contribution?
I don't see the government telling you how to safely invest your money is nearly as intrusive as them taking all your money with a promise that (wink-wink) it'll be here when you need it.
The fact that so many people have been hoodwinked into thinking SS is at risk of not being able to pay is frightening to me. Apparently, people who hadn't even given the issue a second thought, were sucked in after hearing (for the umpteeth time) in the establishment press that "more people believe in flying saucers than believe SS will be there for them." There is more reason to believe the dollar and all investments in dollars will become worthless (all while the US government finds some way to honor a commitment to pensioners in whatever new system comes in) than to believe the monetary system doesn't collapse but SS does.