A little before I was born, but mu understanding is that there was no ethical scandal associated with him. Many people didn't like him because he took over the steel industry with National Guard troops (and thr rail roads too?) to keep the country running during a strike.
He made tough, pragmatic choices. Didn't fool around on his wife. Won elections as fairly as any . . . .
Maybe not that charismatic figure in the FDR/JFK mold, but the right man for the job at hand when the country needed that.