I started a topic on this awhile back that got some really interesting responses. I'm a big reader, too. The biggest thing that bothered me about this supposed "fact" that Aspies don't like reading fiction was simply that it didn't make any sense. The main social problems that Aspies have are due to trouble with non-verbal communication and trouble with empathy/theory of mind/putting yourself in others shoes. When reading, neither of these should be an issue because you don't have to read a book's face or posture and much of today's fiction puts a strong focus on the character's inner life, meaning that you don't have to intuitively understand a character's actions because they're typically explained in black and white. Also, books aren't noisy and baring some specific sensory issues, one would think that books would be a great substitute for human interaction.
Besides, the question you see in things like the AQ test isn't "do you like works of fiction?" but "Do you like reading fiction books?" which implies that there's theoretically something about written fiction alone that Aspies are said not to like. There's not the same supposed dislike when it comes to things like video games, movies, television, etc. which are all also highly fictional mediums. (Baring, of course, personal sensory issues.) Which really doesn't make sense at all, when you think about it. If it were an issue with being able to "figure out" the characters and their intentions and such, one would think that television shows would be much more confusing than books. In television, the troubles with nonverbal communication come back into play. On paper, it would make more sense for an Aspie to dislike television shows and movies more than books, because like I said, today's fiction generally places a strong emphasis on the internal thoughts of the character.
Anyway, people gave some really interesting responses that might be worth checking out if you're interested in this topic: http://www.wrongplanet.net/postt162492.html
Overall, I think this is just another one of those bad stereotypes like "all Aspies are good at math" or "all Aspies have bad hygiene." For a lot of Aspies, this description probably fits very well. But it's not an indisputable fact. It's a generalization, and not one with any diagnostic weight.