There is a consideration to for maintaining after tax accounts in retirement as capital gains are taxed at lower rates than ordinary income.
For many, like myself, my taxable income goes down in retirement as I am no longer getting a paycheck. With an after tax account, I sell what I need for expenses; yes I'm taxed on the gains, but it is taxed much lower. In fact, I almost got to the point of AGI where I would not be taxed at all on capital gains!
With an IRA withdrawal, that income is taxed as ordinary income, and at age 70 1/2 you have RMDs to consider.
The tax deferred advantages of an IRA or 401k works to build assets, but for the time between retirement and 70 1/2, the tax burden of maintaining after tax accounts to draw on is a strategy to consider.