Let's remember specifically that MacArthur disobeyed an order to stand down. https://twitter.com/kairyssdal/status/1266769231309189128

It's one of the non-Roosevelt related grudges Hoover carried after his presidency, that his reputation suffered more for the Bonus Army eviction than MacArthur's did, when he knew MacArthur had effected a small, short-lived coup.

But he apparently calculated it would hurt him more to pick that fight, so he mostly kept mum about it—except for a passive-voice construction in his memoirs. "Certain of my directions to the Secretary of War, however, were not carried out."

Eisenhower remembered MacArthur saying he didn't want to be bothered by "people coming down and pretending to bring orders."

Even taking that aspect of it aside, Roosevelt worried the episode made MacArthur “one of the two most dangerous men in the country” (the other was Huey Long; story for another time)

Roosevelt said MacArthur’s eviction of the veterans appealed to “the Nazi-minded among American leaders"