You want to have your money at retirement in more than one income stream. If you have all your retirement income coming from tax deferred (401k, Traditional IRA, etc) then 100% will be taxable....who here thinks they will be in a lower tax bracket later in life? By having a nnestegg in a tax free pool, you can manage your tax liability much better.
Basic advice: 1) 401k up to company match 2)max Roth IRA 3)go back and max 401k 4) utilize cash value life insurance (VUL, Universal) 5) taxable instruments such as mutual funds
Me, I invest all my money in beer and Bills attire...