So, let me first get this out of the way: What children will actually want to read in 30 years is very, very different from what parents and academics will consider to be great and classic. For instance: I’ve never read Pippi Longstocking. Nor did I know any kids who read Pippi Longstocking growing up. And I honestly think that the qualities that win Pippi such acclaim are ones that you don’t appreciate until you’re an adult who’s ready for some nostalgia, and the same goes for many other “classics”.
Second, you cannot base the entire series off of the first book (I’m assuming that’s the one you read). Rowling created the books so that whatever age the characters were, that was her target demographic: If Harry was 11, she wrote for 11 year olds. If Harry was 17, it was written at a 17 year old level. In the first book, the second book – ok, maybe not so much character development. But once you start reading book 5 (when Harry is 15), there’s tons of it. Rowling specifically sets him up to go through a very “moody” phase, in which he feels all alone and that no one understands him (with, admittedly, good reason). There’s a transition from him being a kid who wants to save everyone to more of an adult who feels an obligation to save everyone and to stand up for what he believes in. The 7th book is really the one to read if you’re looking for greater literary techniques – the storytelling is more advanced, there are more complex plots interwoven, there’s a whole Nazi symbolism thing that’s really great, and a great deal of character development. Which sort of makes sense – I don’t know about you, but I grew a lot more as a person when I was 17 and 18 (which I include because 17 is the age at which wizards become adults, so it’s comparable to our 18) than when I was 11.
I think kids will be reading them for years to come, because children want escapism and parents approve of the message. Children want to be transported to a place where they can do their chores with a flick of a wand, where they’ll have great friends with strong bonds and not a whole lot of backstabbing, where camaraderie and individuality are encouraged, where there will always be a better family just dying to welcome you into their arms and homes, and where they get to eventually win over the school bully and that teacher who randomly hates you. To quote Andrew Futral “Harry Potter is about confronting fears, finding inner strength and doing what is right in the face of adversity.” So to me, if what it takes for something to become a classic is a great use of language and character development, then let me ask: Why is Winnie the Pooh so big? I don’t consider A.A. Milne to be blowing me away with his use of language, and there’s virtually no character development. But these aren’t the things we look for in children’s literature. Instead, we look for a fun ride that will teach our children the values we so desperately wish to instill in them, and that will capture their imaginations so much that they’ll want to read the books on their own.