1. Seemless glass, better viewing for the premium ticket holders, murder on player's bodies. I'm willing to bet 70 - 80 percent of the head to glass concussion don't happen if the old style glass with give was still in place.
2. No red line, faster game = more high impact collisions. Better skating dmen a far more adept at open ice contact.
3. No whistle offsides - again bigger players in motion more often = more plays with speed and thus collisions.
4. Player size/fitness - Bigger men, nuff said.
5. Medical Awareness - Better attention after getting "dinged".
6. Sadly yes, the instigator rule. Savard gets taken out, Crosby goes down initially with a questionable amount of contact. These players that crossed the line would have only done so once or twice. In Cooke's case he is a ten time offender to say the least.
I was under the impression that most of the seamless glass was already gone, and what little was left was going to be replaced before this season: