I once worked with someone who told me that he put in100% of his 401(k) investments in a mid-cap fund because it was in the middle of the market. It’s absurd, but people do think that way.
So aside from the glid path issues that I still have about target-date funds (TDFs), an issue is those plan participants still use them, as one of many investment options, instead of it being the only investment option they use.
A TDF is like a smorgasbord, that one fund that represents a variety of investments split between fixed and equity. Yet, plan participants still treat it as a side dish, instead of a main course investment.