I don't really see it as a lack f respect, and I definitely think that it's rare a head is actually "targeted". Everything is a penalty these days, and the young players grow up leading with their heads, turning into space they haven't cleared, and showing their numbers along the boards. Used to be if you did that you deserved to get railed. The current generation thinks its ok to do it because they'll draw penalties, and everyone hates on the guy who hit them. They also lack the awareness one develops when they assume someone is about to deck them at all times.
Messier whn promoting his helmet was asked what the difference was these days, he flat out said it. "These guys show their numbers and turn into traffic when they shouldnt, it's why guys are getting hurt". Longevity starts with self preservation, not screaming at the ref every time you fall down cause the d didn't buy your move. Then people super slo mo it and dissect it to "see! He turned his elbow two degrees that way right there! Intent to injure! He aimed for his head!". Ugh. Played years of check hockey, I know I never thought the game to the level these guys do but I just don't see that anyone has time on most of these 50/50 hits like the tarasenko one.