There is a very nice, and not at all ad hoc, theistic explanation of why there exist beings who like telling stories. Creation reflects the creator. The creator is the author of the universe, and so there is good reason for there to be creatures who also engage in authorship. I have no doubt that a just-so evolutionary story can be given about the practice of story-telling. However, I suspect that, nonetheless, the fact that we tell stories is evidence for theism over and against naturalism.