Kitten Sith's Mog is probably gone because it would be too much of a hassle to animate it, and he'd take up alot of space or something. Still, he would kick ass with it. And he's there because he's a part of the main team, and it wouldn't be right without it. Feh, Yuffie and Vincent are optional characters, so they'd have to be useless too, right?

I mean, how can you hate a cute, gambling, robotic kitty? You just can't.