I think if you pressed him, Dr Alan Pearce's opinion would be that football shouldn't be played. That's probably a very sensible take on things, but it's more extreme than most people are prepared to accept, so what we are doing is deciding on what is an acceptable level of entertainment-induced brain damage.
Heavy bumps have dramatically reduced since the AFL started addressing the problem. Over the year, you are probably looking at only a handful of deliberate bumps that cause more than the level of brain damage we tolerate from other incidents. Those are mostly illegal and the player is punished.
Banning what is currently a legal bump isn't going to be the fix you think it is. Most of the concussions come from collisions, where no one is at fault. It's just going to frustrate players and supporters when someone shoves someone into te ground and they get put out for 3 weeks.