16. Everyone in those schools would be utterly incapable of functioning in the normal world to which they return for some reason, possessing as they do absolutely no life skills.
17. Sudden apparition of friends or family while fapping.
18. Magic is a clean, renewable source of energy. We could end pollution, oil dependence, etc.
But screw us muggles. Wizards are too busy playing broomball to end global warming.
19. No privacy at all.
Like The Marauder Map which is an enchanted map of Hogwarts, one that shows every inch of the castle and surrounding grounds. People can guess what you are doing at any time