Fiction is entertaining largely because it's relatable (there's not much interesting stuff to get out of a book wrtitten entirely in gibberish, after all), and relatability and belivability are related concepts. It is, however, important for the story to also be exciting, and not just the same mostly boring stuff we do in out daily lives anyway. So a balance has to be struck: when a novel is realistic and understandable so that we don't get caught up in inaccuracies or become lost trying to find the meaning to everything that's said yet also incorporates surprises and unexpected twists or concepts so that we can find the normal in the strange, the reasonable in the ridiculous and the human in the foreign. Nothing shows a person's true character (pun intended) more than extreme situations, such as danger and fear, after all. And, hopefully, those aren't actually things we experience all to often in real life, so in this way fiction is more real than reality and thus more powerful, interesting and worthwhile.
