You know, I was thinking about this in the car on the way home tonight and it occurred to me that what bothers me more about fic isn't that it's playing with other people's stuff (though that is an element), it's that a lot of it is not all that well-written and it frequently strikes me as out of character. I think that's linked to the "other people's stuff" thing for me, in a way I'm not sure I could explain if I had to, but overall, I'd rather stick with canon than read something that's not well done. (There could be an element of MFA snobbery here--I've noticed that my tolerance for poor writing has dropped dramatically since I started that program--but it's not intentional.)

But I'm an anomaly, and I know that. And I don't have any trouble with people writing what they want to write fic-wise as long as they don't hound me about reading it. Live and let live, and all that. :)