I write violent stories. I write dark stories. I write them for my own children, and I write them for yours. And when the topic comes up with a radio host or a mom or a teacher in a hallway, the explanation is simple. Every kid in every classroom, every kid in a bunk bed frantically reading by flashlight, every latchkey kid and every helicoptered kid, every single mortal child is growing into a life story in a world full of dangers and beauties. Every one will have struggles and ultimately, every one will face death and loss. 

The goal isn’t to steer kids into stories of darkness because those are the stories that grip readers. The goal is to put the darkness in its place.

N. D. Wilson, quoted in Justin Taylor, "Why N. D. Wilson Wants to Scare Your Children"

Here's a fascinating article on why British children's stories (which tend toward fantasy) are more popular than American children's stories (which tend toward preachiness and realism). I think the reason British stories (which tend towards fantasy) are more popular than American stories (which tend towards preachiness and realism) is that deep down inside, people know that the universe isn't a soulless machine, but a place of mystery and glory and wonder.