There's an associated danger with fiction: though it reflects how the author sees the world, it may not match how the world really is. Fiction can intentionally or unintentionally invite readers to draw universal lessons which are misleading.

I'd even suggest that some authors, particularly those with strong political views, may be motivated to write fiction in order to give support to their own ideas. It's a blank canvas onto which to project an idealized world, and to fulfill wishes. (If that's the case, it can serve as a mildly negative Bayesian signal about whether the ideas are really true. If there were so many real-world examples illustrating the beliefs, why would the author be moved to write fiction to promote them?)

Apart from politics, plots are more interesting when they're surprising, but almost by definition, surprising plots are less likely to be generalizable to the world.

(Of course, non-fiction can really be fiction in disguise, but at least non-fiction can be fact-checked. To cite a recent Hollywood example, wherever the movie Argo is suspenseful, it's simply made up. Minor spoiler: If you drew a lesson about how going directly against the instructions of both the President and your CIA boss can be a useful tool to cause your boss to suddenly rally around you and later commend your success, you would be gravely misled. Interesting plots thrive on such unrealistic conflict.)