"Since there is no special taxation benefit for dividends on stocks these days, it really doesn’t matter how the money in the plan is generated."
Terry: I take issue with your answer. In you are in the two lowest tax brackets (10%, 15%), then dividends (and capital gains) are taxed at zero. That is a big incentive to keep income below certain thresholds.
But when you WITHDRAW money from a retirement plan it is ALL taxed as ordinary income — at your current tax bracket. That is the answer to the question that was asked — based on whether the plan assets grew from stock gains or dividends.
Yes, it does sometimes move you into a higher tax bracket to take retirement plan withdrawals. But it the withdrawal is a MANDATED amount, (the RMD), there’s not much you can do about that!