Someone recently had the misfortune to badmouth Harry Potter in my presence, since he believes the "gateway" literature argument is specious, and teens should be reading Kafka, not Rowling. Foolish mortal.
Some of my favorite books to read as a teen were various Dr. Who and Star Trek novels, and I usually spent a small fortune on comic books. I'm more discriminating about what I read, but my only qualification is that it be well written, not that it have the seal of approval of my old English profs.
And I've read (and enjoyed) tons of world literature. Do you really think I would have tackled (let alone enjoyed) "The Brothers Karamazov" when I was 22 if I hadn't already learned that reading could be a fun thing by tackling "Dr. Who and the Loch Ness Monster" 10 years earlier? Or that I would have read and enjoyed "Paradise Lost" before I graduated from high school if Spider-man and the Fantastic Four hadn't entertained me and stimulated my imagination years before?
I've read tons of lit, from France, Russia, America, England, Wales, Ireland, Iceland and on and on. I've read mythologies from Europe, the Mediterranean, the Americas, Africa and Polynesia, and I've steeped myself in stories told from the dawn of civilization in Sumer to stuff written in the last five years. I've chased stories like King Arthur all the way down their histories, visiting and revisiting the tales as related by men like Steinbeck, T.H. White, Tennyson, Mallory, Cretien de Troyes, Geoffrey of Monmouth and earlier, back to pre-Christian Britain. I may never have done that if people had insisted I only read "the right" books.
Harry Potter probably could prove to be nowhere as enduring as some of these other stories I've mentioned, but he's still worth reading, even at the age of 34. (And worth re-reading too, I'll add.)
My grandmother was a literary purist, and probably felt that "gateway literature" was a hoax. I'm glad my mother didn't agree with her. I've had a blast reading, and if it weren't for some of the cheesey fun stuff, I never would have had the steam to tackle an unabridged "Don Quixote."
I'll be honest, I don't think I've ever read Kafka. From what I hear he's an acquired taste. Even if he is as good as some people say, that doesn't make him any better or more worthy of reading than something new and popular. Many writers churn out crap, but even they, if they fire the imagination and teach children that reading is worth the time it takes, are worth the paper they're printed on.