I haven't finished the game yet, so I'm not sure how much more character development Basch is going to get, but at this point he could develop into a character who would've worked well as a main character. As it is, we get a largely ensemble cast, and the only thing that makes Vaan the "main" character is that he is the first one you control and he's your in town avatar. And, given how much I hate Basch's outfit, I suppose I'm quite glad that he isn't the one in Vaan's place.