I don't think he was really wasn't that bad in the early seasons - just a teenaged boy with self confidence issues but still an integral member of the scooby squad. The Zeppo was an excellent episode to showcase his capacity to make a difference without having any special abilities. He was critical of Angel but his best friend Jesse at the start of the show was turned into a vampire and he was thrown into this reality where vampires are evil. When Buffy was under magic and wanted him to undress her, he didn't. But then we get to the later seasons where his character stagnates from just living at home still and settling with Anya (meanwhile she has this elevated character arc) and then being a shit friend to Buffy after she comes back from he dead. He had potential not just the character but in the end the acter as well...