I may be overthinking the whole issue, but usually when I hear criticism, I first think "ok, a good game developer listens to feedback and doesn't get annoyed", and instantly after that "but hey, I must make what I like and not let other people affect my work". And then I bounce between those thoughts until I come to some sort of conclusion, usually being either "that's a great idea, I'll add it" or "I don't want/I am not able to implement that". I usually also feel bad afterwards if I've said no to a suggestion, or when someone has made a suggestion that'd change some of the ground mechanics of the game. Getting feedback like "I think you should change the level design" or "You should change that UI" also demotivates me usually even though it shouldn't, because changing basic elements of a game is often boring and tiresome work. Especially if you're working on MMF 2.
tl; dr: I'm too lazy to take proper feedback.