I think heavy carry-ons are the most dangerous thing now. No, they probably won't kill you, but injuries happen at a million times more frequency than injuries from the airplane crashing.

Charging for overhead bin space is very difficult to implement. I would rather replace the big overhead bins with small ones from the 1970's, giving passengers more space around them (less claustrophobia) and obviously preventing you from putting in a suitcase-sized "carry-on".