There is contact every play. How many times have we seen a guy get hit and get concussed and you never would have known it because it wasn't violent. Just like bumping your head on the edge of the table, it doesn't take much. Receivers risk achilles, hamstring, and knee injuries each time they take a step whether they are hit or not due to the torque and cutting they do, same with defensive backs and taking on bigger tight ends. At any point, football is no less dangerous than MMA. Quarterback's may not get hit every play, but no other player on the field takes more shots un-protected than a quarterback as he's throwing and getting ready to throw. Alex Smith's injury is just one to bring up, but there are many others.
Yes, there are rules against targeting, yet players are ejected almost every game, so it hasn't stopped, and never will because of reaction times never being fully equal to the actual event itself.
To either of our points though, it only takes one hit to ruin someone's life and them never walking again or breathing again. It's all dangerous as hell. To your point though, I'd never want to sign up knowing I'm going to get hit in the face whether I know it or not. I've always enjoyed a good fight when I was younger, but I just keep to myself anymore and mind my own business and do my best to treat others how I want to be treated. Funny how that kiddy adage comes back to be how you live your mature adult life.