I have friends working multiple part time job, who end up earning $50K or so a year but none of their jobs have 401k options. So even if they max out the IRA, they are paying much more in taxes than someone else. Also, if I put money in 401k, enough to move my tax bracket down to 10% bracket, I am eligible for EITC. If I do the same in an IRA, I am not. I see that as a problem.
Yes, my DH could save in his 401k to make us eligible for a larger EITC, but I have no access to a 401k. We can both contribute to IRAs, and do, but those have no effect on the current EITC formula for us. So I cannot save as much in tax advantaged accounts as DH can, and the plans have different effects on our taxes. I'd like to have a hybrid plan: independent of employers (like an IRA), but reduces wages like a 401k does, with options for Roth or pre-tax versions, and with limits equal to combined IRA and 401k limits (or higher, of course). Matching would be nice, if possible, but we are currently maxing w/o a match. It would be more fair if any matching were in $ amounts, not %, since lower incomes lose out that way, too. As long as I'm making a fantasy wish list, I'd like the retirement savers credit to be refundable, since we currently get no benefit from that, either, as we owe no tax due to low income and high relative saving rate.
One more thing - since there are spousal IRAs, there should be a spousal account in universal 401ks, too, as long as household income covers the combined contributions.