Of course backcountry skiing is harder.  But who is doing it?  Athletes at the top of the game.  Backcountry skiing is more of a spectical than anything.  Sure, there are some people who are out there doing it without big budgets and the sponsors, but probobly not quite to the extent that these athletes are doing.  Park allows for fun at your local mountain.  Its pretty accessible to everyone.  Its a new, hip thing.  It's a lot of fun to do, go hit some jumps, grab a beer, buy some expensive food, go do it again.  Then there are people who are taking that to the next level, again, as a spectical.  Both take a lot of skill, I'm not going to say one aspect has more skill than the other, but Backcountry has more consequences, and a whole other aspect to it which makes it so rad.