They know the deal they commit to. Don't like it, don't play. But I think their commitment, should actually be a commitment. The school and fans support you, and you should do the same for them. Jumping ship early for a chance at the Pros? That's fine, but I think you should be responsible for whatever years you didn't play that you committed to.
Yes, I realize there is no binding contract when a player commits, but I somewhat think there should be.