What about Arthur Weasley, who's fascinated by Muggles? The (albeit optional) Muggle Studies course? Then there's Muggle-borns, and I'm certain that Hermione would be concerned about her parents. I don't know, I just get the impression from HP that it's a fantasy book. If we wanted to read about the Muggle world, we got a billion other books for that. While I agree that books don't explore Muggle-Wizard relations as much as I'd like, they're still books about the wizarding world, with its warts and all.