Because it's f*cking happy.
Children's literature is the only place where serious themes can be addressed while still allowing for a happy ending. Especially during a recession, these are the things that people want to read about.
Sometimes I feel like there's an unwritten rule (irony ftw) that in order to write serious literature one has to write depressing literature. I blame this on Fitzgerald, who had the audacity to write the world's most perfect novel about a series of tragic, unredeemable characters. From there literature devolved into stories about characters who couldn't hack it in a world that won't forgive them, or characters who could hack it in a world that is so sick and twisted they won't be allowed to anyway, and that's not what we want to read about.
Children's literature knows this. Children's literature knows that we want to read about Odysseus, who was so clever and strong that he prevailed against the gods. Children's literature knows we want to read about Harry Potter, who was so good and loving that he prevailed even against the greatest evil talent there ever was.
Children's literature knows we want the good guys to win, because in real life, they don't.
If you look back at the past ten years of hugely successful novels--the kind that make writers fantasize about totally unrealistic moneys and Oprah coming back from retirement just to talk to them--you will notice a pattern: they all have happy endings. Harry Potter. Twilight. The Da Vinci Code. Even The Road was pretty happy, from a Cormac McCarthy point of view. And I know it wasn't a book, but Avatar wouldn't have earned that kind of money if we just watched all the Navi get slaughtered in 3D, (which, btw, is what actually happened if you believe all that political commentary nonsense). In all of these stories, there was hope. These characters survived. They kicked evil's ass, and found love along the way.
These are the things that are worth living for when you are unemployed and your kids have the flu and your hometown just got the f*ck flooded out of it and your husband has PTSD and there's a high pollution warning and the oil spill and holy sh*t we're still at war seven years later and we still haven't captured Osama Bin Laden and oh yeah like now with instant communication we can watch a live feed of people dying in Haiti after an earthquake. That is our real life, and it sucks. So we don't want to read about that bitch in The Elegance of the Hedgehog who finally starts living and then shoves her face right into a semi's grille. That sh*t's depressing. If we wanted to read about that we could open the Christmas letter from Uncle Roger. Or read the paper. We want to overcome the odds, even if it's only for two hours with a cup of tea before bedtime. Two hours of glorious hero-overcoming-all-the-odds-to-win is enough to allow us to get a full night's sleep and then get up and pay the bills late. It really is.
Literature isn't, or at least it shouldn't be, a self-contained world. No matter how nerdy you were in high school, and how much other kids made fun of you because you liked to read, as a writer you are not participating in some special little club of people who know how to spell antidisestablishmentarianism. You are not isolated. This is not about your art. You are a storyteller. And everybody reads stories--or at least watches them, or plays them on a controller, or listens to them. Stories are metaphors for ourselves, for the way we treat conflict and difficulty. Stories are a very human institution, and they're what allow us to picture ourselves as heroes, as people who don't give up, as chosen ones, when really we are all very small and not sure of what to do.
So of course adults read children's literature. Because we still need someone to tell us that it can be done. That we are heroes. That even though we are older now, we can still do anything we want to, and be anything we strive to be. These are things we need, desperately. So however important and tragic and well-written All the Pretty Horses might be, guess what? It doesn't give us what we need.