Rangers, rogues and paladins all can dual wield just fine. I've used every one of those characters or seen them played in my games. Monks pretty much never dual wield because martials arts, however you don't want monks to turn into always dual wielders either.Considering that only one out of four of those classes will sometimes dual-wield right now, that certainly seems like a strong argument to remove the bonus action. Especially considering that 3 of those 4 classes should really be commonly dual-wielding, at least by trope.
Removing the bonus action basically makes all those classes listed above be no brainer dual wielders in a featless game. With feats polearm mastery is a little better for some but does cost a feat so it's a wash. GWM would be offset with my propose by a -5/+10 feat for TWF