When a player commits it should be binding, period!! If he decommits, he should have to do the same thing as if he had already signed.... sit out a year. I promise that would solve the problem.
Except that the NCAA doesn't recognize the chance to commit before national signing day. All the talks of commits beforehand have nothing to do with the NCAA so there's little they can actually do about it.
The only commitment recognized by the NCAA is a signed letter of intent. Verbal commitments prior to that time are nothing more than words and are pretty much as meaningful as preseason polls.