Game mechanics aside, I have to agree with Rosen's second point. The examples listed in the OP are creative and fun uses of magic, distracting without necessarily being debilitating. Giving a foe a wedgie, causing his cloak to flip over his head, jerking a loosely held item out of his unsuspecting grasp, tying his shoelaces together are things I can see magicians (and especially their ornery young apprentices) attempting to do. I'd let them give it a shot and not get too worried about the rules. If you can't have fun with magic what's the point?