I hope Castille's hit would still go without a pentalty today, unless a ref got flag happy. That's pretty clean imho... shoulder to chest, with a lot of force behind it.
I, however, do agree with the overall idea that we should better protect players, especially trying to limit contact with the head and neck areas. One analogy I like to make is with an armed soldier. Being a rifleman is an inherently dangerous job, but, that doesn't stop people from coming up with better weapons, protective gear and strategies. Just because something is inherently dangerous doesn't mean we can't try to make it safer.
But, in some cases, I think it's hurting the game. It's almost reached a point where instant replay should take a look at some of the "unnecessary" hits in the game. Referees can review "illegal" hits to see if an ejection is needed, but, the penalty always sticks. That's not right to me. There were a few "illegal" hit reviews I saw last year that, after watching it on replay, I believed didn't even warrant the penalty. But, I doubt they'll ever change that.