I honestly hate wearing helmets and think there uncomfortable and everything, but I've known people who've had concussions and have actually split there head open, even when riding on a trail; even though I hate it I wear one just because you think about it and one blow to the head is all it takes.
Agreed. You don't need to be in the pipe or landing a big kicker to get wiped out. I've had the last 3 weeks taken out of my season (and at least one more week) from an accident I did on a hardpack groomer. I'm glad I had my helmet on.