I am relatively speaking a nobody, but I have two old college friends that played pro ball and they both say that team trainers and doctors essentially threw your butt out there as long as you could answer a couple of questions, even if your ears were ringing.
Add that onto the fact that Joe Horn and other recent NFL vets are saying that they were given painkilling drugs (Toradol) that are now causing serious after-effects related to head traumas and you should be able to see that this isn't just some simple issue about players trying to get something over on the owners when they "already knew the risks." Instead it is a complex issue involving new knowledge and how to incorporate it into the evolution of the game and the game's treatment of past players.