Re: We are approaching a state where no one will know how to play football.
I like the rule. Too many times I see a defender go down low for a tackle, the offensive player lowers his head, and the defensive player is hit with a helmet to helmet penalty. And the offensive player is unconscious on the ground because HE lowered his head.
Don't give the nonsense about your chest being left open. Like Jeff Fisher said, "use your shoulder."