A terrible character with a terrible justification for being a terrible character is still a terrible character.
Vanille isn't a happy-go-lucky character, by modern series standards that would be Tidus, and he wasn't too bad.
Vanille is a walking fetish for a very particular sort of person, expect to see a lot of people with moe avatars and dancing asian girls with lolita tendencies sticking up for the character. The rest of us who dared to buy this are just forced to suffer for it.
She's the worst character in the history of the franchise, and in some of the later iterations that's really saying something.
if you hate all those things, why are you playing a final fantasy game?
He's not playing it, and despite what the series is for you, it wasn't always the same for some of the rest of us.
I'm playing it however, and I can dig the neon roller coaster of battles and flashy stupidity, but that doesn't mean it's not fun to swing a stick at that stupidity or wish the games party consisted of just Sazh.