The whole rule is absolutely ridiculous in my opinion. The point of the rule is to make it safer for the players (right?), but the only time I ever see it used is when a player does a little touch foul/grab to stop a fast break. Ironically, it encourages a defender to keep running to the basket and foul the crap out of the guy while he's mid-air going for a layup, which is much worse.
Or maybe I'm wrong, and the rule is simply to encourage more fast breaks/breakaway dunks. But even if that's the goal, it seems like a bad rule because players just ignore it and foul anyway.