My thought is that current federal marginal tax rates are as low as they ever will be and will be higher when I'm retired.

I have never invested in a Roth IRA because a bird in the hand is worth two in the bush. Plus you figure your current marginal tax rate will likely decrease if your total annual income is less than your current annual income. So you get a tax benefit now at a higher marginal rate and when you start receiving your withdrawals, your marginal rate will be lower.

Plus I don't trust Congress. When the fiscal reality they have been ignoring comes home to roost, they can just say, hey all of you folks that had Roth IRA and 401k, we simply cannot afford to have you receive your retirement money 100% tax free.