I will try to stop with the half-baked theories, but I am not sure I can. Maybe turn up the heat in my brain? Is that stretching the metaphor too far?
Here's the thing: YA is a relatively new genre/category. And people tend to freak out about it, as they do about so many things teenaged and sexual and oh my god my baby. There is a lot of talk about what is and isn't YA, and what makes something YA, and what would have been called YA back in the day before it existed. Things like, say, Carrie by Stephen King: about teenagers, scary, sexual.
My guess is if Carrie were to be published now, it would be YA, and immensely successful "crossover" YA at that. Meaning teenagers would love it, and grownups would surreptitiously enjoy the heck out of it, and it would become a movie etc etc all the strange markers of book success these days (not so different from what it did experience, except that it was the teens who were surreptitious).
But does that mean that any book about kids, especially ones with futuristic elements, is YA? Here's what happened at my house: somehow, one of us gave Diana a copy of Never Let Me Go by Kazuo Ishiguro. And beware, spoilers do abound below, though I will try to be circumspect.
First of all, she devoured it. But here's what it seems to have done: broken her heart. Because (and here's where the half-baked aspect comes in) in YA, ends tie together. Things make sense. Rings are found and brought to the right place, justice is served, vengeance is savored, stories end, things have meaning. But in this?
The characters ring so true, and what they are searching for is meaning, how to make the stories of their lives make sense. But it never comes–because that's the painful secret, really (also the painful secret of being adult, I hazard a guess? That it is highly unlikely we are special, or singled out, or destined for some great meaning?). It's the antithesis of what they read in YA. It's not: you might not realize it, but you are chosen and special! But rather: You think you are chosen and special, but you live in a vast, chaotic and uncaring world, in an uncaring universe, and all that makes you feel special and particular is as nothing to it.
Now my own heart is feeling broken. But I do think I have identified it to myself. And you know what? I am very happy if Diana and all her zany compatriots can indulge in reading about worlds in which unsuspecting girls find they have superpowers, and they battle evil, and it matters. And then later they can read beautiful novels that acknowledge that is sometimes doesn't. And there is room for both.
But it does break my heart.