Once you hit retirement, you are forced to withdraw from your regular IRA, a taxable event. You do not have to withdraw from a roth. I've been moving money from my regular IRAs to roths for decades. Now that I'm getting a couple of years from 70, I wish I had moved more and paid the taxes at that time. Now I'm moving only the amount that keeps me around the 12% tax. It's still going to be painful having to pay the taxes on the withdrawals along with the social security which I'll start at 70, the latest possible and largest amount time.
Of course, if you don't have much money in your retirement accounts, it makes little difference anyway.