I didn't have a problem, either, and Big D put it perfectly... I mean we've all played tons of RPGs like this, I don't see why it was such a big deal. He's a kid with humble beginnings who saves the world. How is he irrelevant?

I also like the fact that FFXII is a "coming of age" story for him. As Vaan sees the world, his perspective broadens. And that's beautiful.