I'm thinking the neck brace is one of those "well, the other BMXers aren't wearing helmets..." type things?
But with all these phenomenal riders in wheelchairs and phys therapy lately(seems like it's contagious right now) it's starting to sound like such a not-bad idea. But it would have to be like a seatbelt: wear it ALL the time or don't bother at all. How crappy would you have to feel after you wake up in a hospital bed with no feelings in important places knowing your neck brace was in your gear bag? Hell, I mean look at where/how Tara went down. Couldn't imagine wearing a brace there... Damnit that sucks.