[The-Pro]

Neither do species. It's just a generalization for the sake of brevity and efficiency in communication. A less useful one than species by a good bit, to be sure.

Also, race isn't just a matter of skin color. It's usually also associated with other physical features, which are becoming less distinct over time due to fast transit and interbreeding. 'Asian' doesn't always describe a uniform skin color, but most people can tell an 'asian' from a 'Caucasian' pretty easily, due to features of the eye, its shape, the shape and size of the various bones of their face, etc....