@Purple:
The truth of the matter is that, at this point, the culture of the game is too ingrained into the idea of heavy tackling. Light tackles or just touch football is just a K-12 sorta deal at this point, and too much build into the society is based on watching these people crash into each other. Removing the helmets at this point in favor of leather caps would simply promote more substantial and more apparent injuries, and there would also be no way that the public would support something that would apparently "seem" more dangerous.
This is of course neglecting other activities such as people going skiing or snowboarding without helmets on because "it isn't cool" in spite of those winter sports also being very capable of producing head trauma. No doubt that people feel more invincible with a slightly harder egg to crack, but I would say there's more of a problem that the NFL hugely downplays the very probable risk that, yes, you're going to be losing a few screws playing the game every week, and it's a big reason why that cracked article before surmises that football will become less mainstream in the future because no matter how you play today's version of the game, there is a pretty big risk involved. As long as people currently see more of the glamor and stardom that being a player has, then this subtle risk of brain damage is the furthest thing from their thought.
That and blowing their wealth.