"There's no reason why fiction has to be the equivalent of a realist painting. There's no reason why all the literary fiction writers of the world have to pretend they are Richard Estes. Why not be Hieronymus Bosch? Why not be Max Ernst? You can do anything in fiction. There's no ethical thing holding you to accuracy in reporting. So 

why 

   can't         the monkeys fly? Why can't we live in a world where everybody eats blood oranges? There should be in fiction an element of experimentation, and people who have a problem with that remind me of the kids who carried, I don't know, War and Peace around with them in high school, just to be seen carrying it. They feel like they're being judged by what they read, so they want to be high-purpose and impregnable. But there's no reason why Kafka, say, should not be regarded as writing science fiction. A man turns into a bug - please! Calvino is just as much a writer of science fiction and fantasy as Tolkien. So is Borges. I just don't understand why people are so ridiculous about all these labels." 

Niffengegger. P&W. 2009.