Best to withdraw from both Traditional and Roth 401k?

Many articles debate Traditional OR Roth 401(k) but I do not see why contributing to both is not the best answer. I have been contributing to both and want to know if there is a flaw in my logic. To keep the numbers simple, lets say I currently make $75,000 and when I retire I will withdraw $100,000 per year. I... show more Many articles debate Traditional OR Roth 401(k) but I do not see why contributing to both is not the best answer. I have been contributing to both and want to know if there is a flaw in my logic. To keep the numbers simple, lets say I currently make $75,000 and when I retire I will withdraw $100,000 per year. I will take $50K from my Traditional account and $50K from my Roth account. Since I only owe taxes on the $50K from my Traditional account, my taxable income should only be $50K even though I am pulling in $100K. Therefore, my tax rate when I retire would be lower that my current tax rate because I have less taxable income. If this is true, why do most sites debate one type of 401k vs the other and not recommend both? Or do I have flawed logic?
3 answers 3