If you have a rollover IRA from a 401k (or equivalent) plan, then its withdrawals are taken as ordinary income, too. But, the contributions which went into them originally would have been taxed as ordinary income. And, if you put money into them back in the 1990s as I did, then the marginal rates were much higher than they are today. My (federal) marginal rate back then was 28%, which fell to 25% starting in 2001 and has since fallen to 22% this year. (My state income tax rate has also fallen.) This greatly offsets any increase in taxation due to taking out all the money as ordinary income instead of some combination of ordinary income and the more lightly taxed dividends and cap gains. And that doesn't include any company matching funds which were the closest thing to "free" money you can find.
A quick and simple numerical example: I contributed $100 to the 401k back in the mid-1990s and it was matched at 75%, so I had $175 working for me. The tax benefit meant that it "cost" me only $72 ($100 - 28%). I've already made 143% on my investment at Day One. Even when taxed as ordinary income at 22% I still clear $137 for a 75% return.