Not sure why someone didn't think of it sooner,. They've been doing it on surfboards for a while now. Snowkiting.
Here's a NYT piece on it.
I imagine you could get in a heck of a lot of trouble really quick if the wind and terrain conspire against you. Trees, cravasses, cliffs. power lines. Oh my!
On the plus side, you prbably don't get cold like you do at a traditional hill because you never have to chill in the chair.