See, I don't think that is bad voice direction. Yes, he's grating. That's kind of the point. He's being a whiny teenager and whiny teenagers are *always* grating! :)

Basically, I think the voice acting in FFX gets a bad rap and I will defend it to the death (except for Yuna who so often sounds stilted and wrong, and I think that's largely because she was trying too hard to make her speech patterns match the Japanese mouth movements).