401ks are still related to the person’s place of employment, so they don’t actually solve that problem. I’d rather see us ditch them in favor of higher contribution limits to IRAs.
Defined-contribution retirement plans (401ks and IRAs) in general are not an adequate replacement for defined-benefit ones (pensions and Social Security) because, frankly, people are too stupid on average to plan properly for their future. And even if you think stupid people deserve what they get, it’s still a problem that affects you because of the collective burden massive numbers of indigent elderly would put on society.
401ks never should’ve been created, and the replacement for private employer pensions should’ve been an expansion of Social Security.
(I say all this as someone with much larger than average retirement savings who’s aiming for FIRE, by the way. This is a critique of the system from someone who has benefited from it, not sour grapes from a stereotypical poor millennial.)