I was talking to one of my fellow writers earlier today, and in a discussion about one of his stories, he apologized for being "manipulative" in a particularly emotion-driven scene.
Now, I suppose it could be debated whether or not it's actually manipulative to do something specifically to get an emotional reaction out of a reader. On some level, I think that's pretty much the writer's job: after all, why do people read stories at all, if not to experience some sort of emotion, be it sadness or joy or terror or even a cheap thrill?
Of course, I do think that it's possible for the writer can pull a cheap shot for no real reason other than to get a reaction that might otherwise be unwarranted, and nine times out of ten I'd probably oppose that. There are times when even that can work, though, I think (a certain character death in the second season of Buffy springs to mind). Like everything else a writer does, though, one just needs to be careful with it, I suppose.
On the whole, though, I think that the entire premise of writing "fiction" is that we take situations that need to be carefully massaged so that they can be masked as something that would actually happen. That's pretty tricky in and of itself. But in the end, the goal is still to convince the reader that what they're reading is real, and to instill an emotional response based on events and actions and people who aren't actually real.
Is that manipulative? Maybe on some level, I suppose. Perhaps one of the bigger tricks in writing is to also mask the manipulative moments so that those aren't obvious, either.
(And I still maintain that the scene in question that started this thread of thought wasn't manipulative. Or, if it was, no more than the situation demanded of it. :3 )