Current class balance is predicated on the existence of preps. Wandless mage being at somewhat of a disadvantage is a feature, not a bug.

Removing preps entirely means some classes would probably need to get boosted. Ragers might need to get toned down as well.

Also, what are you counting as a prep? Flight? Enlarge/reduce? Frenzy? If magical flight doesn't work against PCs then arials and cloud giants suddenly become way, way more attractive.