The problem with Yuffie is not just the Wutai Materia quest, it's the fact she's a self-centered bitch that looks down on everyone and treats the rest of the party like trout; like when she blows off Barret after he tells the party about his hometown and his connection to it's destruction before going to the Gold Saucer. Also, being a decent party member 3/4th of the way into game when you acquire their ultimate weapon (of which this happens to most of the party anyway, so it's not that special anyway) doesn't redeem the fact she's kind of dead weight for the first 3/4ths of the game. Her biggest problem is that she's more annoying than funny, which is the issue I have with all of the Hyper Genki Girl characters in the series. Her back story isn't enough to to redeem her negative qualities. I mean at least when Edge did the whole Arrogant Proud Ninja thing, the game went out of it's way to put him in his place.