i don't agree with that at all. lowering the head or moving it to the side a couple inches is not a big deal when the offensive player is in a defenseless position....and that is the only time they are protected. even ted brushi, a hard nose player in his day, said the same thing on espn radio today. i know a lot of defensive players will rant and rave, but they will adjust and the game will be fine. i remember when players acted like it was impossible for a pass rusher to pull up under 3-4 steps....now they magically do it fine.
I get what you are saying. Yes, people learn to adjust their play based on their pocket book alone, but if a LB or Safety runs down a RB, WR, or TE and the player about to be hit moves ever so slightly the trajectory of the collision is now altered & just like clockwork the defensive player gets heavily fined. When was the last time you ever heard of an offensive player being fined? It's almost non existent.