Mercy's been reading and re-reading Jane Austen ever since she learned that Austen was Rowling's favorite author. Susan borrowed my copy of Christian Symbols in Art last evening. Gracie and I sit in the back of the church together and (in whispers) try to reverse translate the liturgy back into the original Latin. The whole family watches Dickens together (Rowling's other favorite author) on DVD - repeatedly.
On the other hand, Rowling, in spite of meeting thousands and thousands of children, has never had one of them thank her for introducing them to witchcraft. Many children have, however, picked up on the political and religious themes in the books.
It's perfectly evident to me that the Potter books are a 'gateway drug,' so to speak, to three millennia of great literature. Why else would Rowling have had the first book translated, at her own personal expense, into ancient Greek and Latin? Is there a lucrative market for what we used to call 'the sacred languages'? Look at the sales ranks of the books on Amazon, and you'll see that these translations are a labor of love. Love of what? Love of learning. Why else would Rowling put so much Latin into these books? Why all the myriad of literary references, from "Guinevere" Weasley (daughter of Arthur) to a tattling little cat named Mrs. Norris? (Read Austen's Mansfield Park for more.)
Rowling studied the classics at St. Michaels, a school founded almost two centuries ago by William Wilberforce (of Amazing Grace fame, link here). There, like Hermione (which is close to a word that means 'she interprets' in Greek) she read voraciously and absorbed whatever she could.
Rowling made a bet which, if it had been stated explicitly, would have been rejected by every large publisher in the Western world: She wagered her labor and reputation on the proposition that children were hungry for the good stuff. That they had eaten their fill of literary junk food, and wanted the stories, the words and phrases, the atmosphere and the 'feel' of the greatest stories every told. Happily for us, Rowling kept her mouth shut and walked her manuscript past the sleeping dragons of political correctness and 'realistic' (meaning sexual) teen lit. It worked. It's just like they say at Hogwarts, "Draco dormiens nunquam titillandus," that is, "Never tickle a sleeping dragon."