...What's so happy about being the most disappointing series, really?
Though I don't think the wording of this poll title is all that good to begin with. The word "disappointing" means "not living up to the expectation". I think SAO is voted the most disappointing just because the series was really popular at first, while the rest...well, not that many people even bother to watch it to begin with, so of course, no one will be "disappointed" in them. *shrug*