It's used for different reasons and to different effect. YA has done things with writing that we have never seen before, and has paved roads that didn't even exist until recently.
I think that in YA today, books have become the seed of shared, fan-built experiences, rather than a self-enclosed product, like, say, S.E. Hinton's
The Outsiders was. Teens might have read that book and talked about it between themselves in the 70s and 80s, but for something like the
Twilight series, there's fanfic, fan art, book discussions all shared across the internet and social media. It's a much larger, more immersive, and nebulous thing. I don't think it's the "joy of reading" so much for teens, or that Twilight and Harry Potter were so well-written and groundbreaking. It's just that reading the book allowed teens to join the club and participate in this wider realm that had accreted for whatever reason, that everyone was talking about, and express their own opinions and artistic and literary desires. It's actually kind of random and awesome.
Current YA also has a freedom of subject matter and themes in it that only used to exist in the wildest, most-out science fiction and fantasy, but without the dryness (Frank Herbert) and pseudo-myth (Tolkien) of science fiction and fantasy, which can be very appealing to readers, especially young readers. If I was 12, I certainly would have read
Divergent rather than
Dune. It would speak more to my experience as a teen girl than
Dune. But in my time,
Dune was all that was available
.
I would also say that many YA novels, especially dystopias
, have come out of the fanfic AU (alternate universe) writing in that they are high concept. There has always been AUs in fanfic, where familiar characters are placed in non-canon settings, often fantastic ones, as the result of plot bunnies or to test them to the limits, but in the late 1990s, this type of story soared as fanfic authors vied to see who create the most out-there scenarios. So you had stuff like Legolas and Aragon transposed to ancient Rome, and the Harry Potter kids all being vampires, or Philip Marlowe detectives, or whatever. Some very inventive stuff came out, that would have never in a million years been accepted by any publisher anywhere, because A) it was fanfic and B) it was just too crazy and strayed out of genre, and often too prurient, even though many of these stories were very well written. But that anything-goes inventiveness did find its way into YA where it found a home.
And that is probably very good for YA writers right now