He comes off has being quite an idiot but guess what he is and to make him more hated he has effeminate facial features to make you more angry.
compared to cloud and squall he's a fanboy/fangirl dream. he's weak has hell the type of person you want to hurt if you saw him in the street.
fanboy/fangirl: isn't tidus great?
normal person: if i want something to whine or complain i'll get a parrot
fanboy/fangirl: am gonna get a tidus costume
normal person: okay am gonna get a sledgehammer!!!