Is there any reason to have a savings account if you have a Roth 401(k), which allows early withdrawal of principal? If pooled together, couldn't you get the liquidity of a savings account and, if you don't end up needing the money until retirement, the tax free growth of the Roth?
I realize there are some potential psychological benefits of having money that you don't touch until retirement, but is there any other benefits to keeping them separate?