This is a great example. When I was a kid we did not have such ''lowly grade level'' books to read. What did I read as a kid? Lord of the Rings/The Hobbit. Edgar Rice Burrows. Issac Asimov. And all the books we would now call 'classics' like the works of Mark Twain, 1984 or Uncle Tom's Cabin. I had read most of them before I was even a teen. Sure, I read Bunnica(the vampire bunny that only eats vegetables) when I was like six. But well before the time I was ten, I was reading 'adult' fiction.
My generation did not have Harry Potter, Twilight or any of the other current popular fiction that ''talks down to kids on their level''. I was reading Gulliver's Travels as a kid, a book that I'll bet that few under the age of twenty have read(unless 'forced' to in school).
Hardy Boys, Nancy Drew, Tom Swift, Enid Blyton's Famous Five.
Even in the field of fantasy, there were works like Lloyd Alexanders Chronicles of Prydain, which were definitely written to a lower grade level.
Our generation was just as bad as the current generation. Actually, if anything I would say that the main difference is that adults of previous generations did not use to read children's books, and thus you never had the mega-successes of Harry Potter or Twilight or Hunger Games. Children's books stayed in with children, and did not migrate to society at large.