From the part of my brain that ponders irrelevant things: Why does Harry Potter have glasses, anyway? I don't mean why did he have them in the first place, but why does he still have them? I mean, if wizards can come up with "Skele-grow" to re-grow the bones in Harry's arm, why can't they come up with a spell or potion to fix his eyesight? Then again, whenever he loses his glasses, he doesn't seem to miss them much. Maybe they're just for show.

I'm thinking this may be a good example of why one should always put limits on magic in fiction. Harry Potter magic doesn't seem limited, really, except for having to learn spells before casting them.