401ks have recently been a subject of interest to me. In particular, while I love the program conceptually, using a Federal tax benefit seems like a great way to leverage private dollars, increase the income security of seniors, provide low cost financing to US corporations, and provide individuals greater control of their financial assets all at the same time, it seems to have failed to achieve all of these goals.
Now, something I've said more than once is that properly doing social science means paying attention to observations and not getting led astray through deductive reasoning from shaky priors. In the case of 401ks, no matter how rock solid they seem conceptually there seems to be little data that people are actually behaving as predicted. Not being an economist I'm not going to investigate this at length but I'll be posting links as I come across them to back up this argument. Reading more on the topic is what has led me from being a big fan of the program, it seemed like a great way to change people's habits and lead to more efficient outcomes in the abstract, to feeling that it is a regressive waste of Federal money that hurts the poor and benefits primarily the well off.
This isn't to say that a different forced savings program that involved private accounts wouldn't work, that's a separate subject, just that programs structured like the current 401k don't seem to achieve the results that justify this tax preference.
[For now, this is crude and unsorted; pretty much anything I could find in places I usually look. I'll organize and update it later.]