The problem is the sheer weight and speed of the players. The collisions are horrific.
Solutions:
1. Put a weight limit on the players?
2. Go back to single platoon football?
3. Shorten the games (in other words, limit the number of plays)?
4. Make the players play without any padding other than a helmet, similar to lacrosse???
I think a combination of these items might make the game safer
You could also make an argument that taking the helmet away would help. Without a helmet players probably would stop leading with their head.