There isn't any sort of point whatsoever. But, if you look at it like that, there's no point in the entirety of Wizard101. It's fun, we do it. that's the reason. And who wouldn't want to be chosen to represent a school of magic?
I second everything Wolf has said, and would like to add, the NPC student teachers (mindy pixiecrown, nolan stormgate, etc.) are really annoying so we don't want them incharge of us. Even if it is just pretend! :)