I have not read any of the Harry Potter books or seen the movies, so I can't speak to what they contain. However, I do think that we need to be very careful, especially in children's books, in dealing with the occult.
But the fact remains that the Wizard of Oz is straightforward populist socialism.
That was pretty clear...
I agree with you. If people think that Harry Potter novels, or even any-and-all fantasy fiction, is a bad idea for their children, that's their judgment call to make as parents.
I also agree (with somebody-or-other) that the marketing of genuine (or pretends-to-be-genuine) witchcraft-related material with fantasy fiction is a problem. I even complained at the bookstore when they had Wicca books in the same display as Tolkien items!