For better or worse football is penalizing hitting defenseless players now. I think probably for the better and we'll see the same change in hockey. For sure players need to be aware and avoid putting themselves in dangerous situations but I don't think a failure to do that gives license to their opponents to make a play that has a significant risk of doing permanent harm. There has to be some onus on players not to make a dangerous play. You can still hit a guy with his head down, but lining up a high speed head on collision like this shouldn't be ok.
I can guess what the reaction these ideas will be. If you think I'm wrong I don't think you've understood the severe consequences of concussions or how public opinion is trending on the issue (outside of the macho "just keep your head up" culture).