You assert "if the problem is low contributions, that is not the fault of the 401(k)", but that conjunction doesn't hold. To wit: is it possible that the requi

You assert "if the problem is low contributions, that is not the fault of the 401(k)", but that conjunction doesn't hold. To wit: is it possible that the requirements for participation in a 401(k) are such that fewer and fewer people can actually contribute to one for a significant period of time? In that case, low contributions would be a result of the 401(k)'s structure, and your conjunction's consequent would be false.