How exactly does one play tackle football and not lead with the head? The human head still sits north of the human shoulders, does it not? How does one lower the shoulder, w/o lowering the head?
Proper tackling--which is rarely taught on any level--involves bending the knees, lowering the shoulders, and bowing the neck to keep the face up. Put the face on the playside number and shoot across the body to the football, bringing the shoulder and shooting the hands to wrap up. A player is almost 99% less likely to hurt his head/neck by bowing it rather than bringing it forward.
Leading with the head is much less violent when it is done face first.
Now, my problem is that the NFL is so fast that you lose technique trying to make a play. That's why I question the ability of the league to punish players for this. But if a guy puts his head down, you punish him so that he'll think twice about breaking technique.