There are different dimensions of fiction. Fiction can be used to teach lessons in science (hard science fiction), history (historical novels), logic and attention (some who-dunnits) and of course literature. But fiction can also be optimized solely for consumption by engaging our curiosity with surprise without depth, our empathy with crime without reason and our happiness with humor without relation.

I tell my sons nighttime stories that secretly teach ideas and I prefer fiction that does so too.

See also http://lesswrong.com/lw/jnv/brainstorming_childrens_stories/