NE: We know that with Transfiguration it would be simple to make his glasses look nicer, and if Madam Pomfrey could fix Hermione’s teeth, regrow Harry’s bones, and basically anything else you can imagine, she could probably fix his eyes. The question is more why nobody does/did this. He may have just liked his glasses… after all, we have no evidence that they were still broken after he came to Hogwarts. (In fact, didn’t Hermione fix them on the train? I could be wrong about that- but Mr Weasley for sure fixed them in Book 2.)
Perhaps it’s linked to Gamp’s Law. Or maybe nobody was in the mood.