I agree that race should not really matter as its a fantasy world. However as Joshcfl08 says, there is a mix-up between the FMV and other cut sequences. Sometimes this is good, sometimes not. In FMV, Tidus looks like a weird mixture of races which I personally think is freaky, Wakka looks amusingly fat and Rikku rather cutely Japanese/anime. I guess its whatever floats your boat in the end.