Man Alaric, every time I read about your crash it makes me cringe. I don't think I realized that you can't snowboard anymore? Doctor's orders, or are you just done with it?
I know you're a young guy and even with a TBI (Traumitic Brain Injury for those who need clarification), people do come back and ride. Keven Pearce comes to mind. There was a documentary I put up about another up and coming pro snowboarder he suffered a TBI and his long road back to getting on his board. Anyway, neither here nor there. If you can't ride anymore you can't ride anymore. That sucks. Neither one of these guys mentioned are going to be riding at the level they did before the TBI either. Best of luck to you.
As far as helmets go. I ride in primarily primo conditions. Powder. Even so I always rock a helmet. In the backcountry, things are not marked. Sometimes you choose an area that looks great and ends up having less than idea coverage. Taking a tumble in shallow covered rocks can be bad for your problem solving abilities. A helmet does not bother me and is just a little extra protection. It certainly does not make me braver or more reckless.