Have them wear leather - the way the game is supposed to be played.
I’ve heard that the old leather helmets provided good protection. Today’s hard shell helmets can be used as battering rams.
Another factor is that the players have bulked up so much in recent years. Years ago, 300 pound players were rare. Now there are huge numbers of such players.
There’s a big difference between being hit by a 220 pound player and a 320 player. The laws of physics are involved. Force = mass x acceleration.
“Have them wear leather - the way the game is supposed to be played.”
I said the same thing about hockey. Get rid of the cages and there would be less high sticking.