There is strong pressure for American schools to de-emphasize fiction and focus more on nonfiction, because of the belief that nonfiction provides more "academic" language. But studies suggest that fiction may be the bridge between everyday conversational language and academic language. Self-selected reading, which is largely fiction, provides us with the literacy development and background knowledge that makes demanding texts more comprehensible. Studies also show that fiction exposes readers to other views of the world and increases the ability to deal with uncertainty, which is crucial for problem-solving.
Krashen, S. 2015. The Great Fiction/Nonfiction Debate. (Published as: Fact or fiction? The plot thickens.) Language Magazine, 15(3): 22-27. Available at: http://languagemagazine.com/?page_id=124655 and