Helmet to helmet has been a no-no for years. It's "outside of the current NFL rules" which is why flags get thrown and fines get levied. Not just for hitting QB's. It happens to WR's and RB's too.
Wentz was stupid for not sliding, that's his playing style and it's going to shorten his career and cause him to miss games. But Clowney broke the rules.
Chop blocks, horse collar tackles, whacking defenseless receivers and plenty of other rules have been put in place and every player and coach knows what they can't do.
I am always glad to see a rule that protects a player from injury unless it's senseless. The problem I have with the NFL is they wait often wait until players get hurt. A good example of that is the horse collar tackle. A few players had knee injuries from that, they acted too late.
Does the NFL go too far in some cases.......well yes and I think we all agree on that. But overall most of the rules changes have been smart and pretty easy for players to comply with.