LogFAQs > #967882636

The particular problem with the suspension of disbelief is that fantasy creatures are usually small-knit homogeneous communities. Whether created or evolved, extraordinary variances in skin color aren't going to inherently make sense to the viewer unless given an explanation of the creator god purposely doing that or the community consisting of creatures from varying regions that diverged over time. So it's less that they "can't" have variances and more that you wouldn't expect them without a much larger, widespread population like humans.

At the end of the day, it really doesn't matter because it's all down to real world casting choices, but the logic behind some of the arguments about it can get weird.