There are different types of quicktime events. If it's something that's really integrated into the gameplay, (say, for example, pressing 'A' will always cause your character to do something specific in a cutscene) then I just think of it as another control. Other times, I really don't know what they're doing there, and it just seems like a lazy gameplay mechanic that they couldn't be bothered to figure out another way of doing.
I think the aspect of quicktime events that really annoys people is just that they come out of nowhere in some games without you being at all prepared for them. All of a sudden you just see, "A, B, A, X, Y," and, if you miss it, all scrunched up in a tiny corner somewhere, you have to start again.
Plus, if quicktime events aren't optional, it's basically forcing you to choose a certain option in a cutscene in gameplay, whether you like it or not. It's like, "Why do they even bother to make this cutscene interactive when you don't have any input on what your character does, anyway?" If the event is scripted with a certain outcome, why pretend to give the player any control over it? oO But then, that's just me, having been spoiled by my open-ended, choice-heavy games. =P