"Aang's entire people were wiped out, and nobody holds that against him." Because both Aang and the story recognize this as being a failure on his part, and even though there was realistically very little he could have done to change things, it is still something Aang experiences lifelong guilt and remorse over. Meanwhile, Korra was entirely capable of preventing her uncle's plans from coming to pass, arrogantly dismissed everyone's warnings, and refused to ever accept accountability for a decision that negatively affected not just her and the world, but all future avatars. It really does baffle me how Brike ever created something as good as the original show when THIS is how they view their own characters.