By an amazing coincidence, I was making that very rant just the other day. Although I also made mention of the fact that it seems to me that authors seem to write AU "fanfiction" like that because they know if it's fanfic, people will read it. I don't think they consciously think like that, but that's the way I feel when I read a fic that has the GW boys as dragonriders of Pern or whatnot.