It's just another adjective.

If there's a black guy walking next to a white guy and I want to tell you something about one of those two guys, why should people be fumbling for words when there's a perfectly easy descriptor to use?

"Uh...the one who's about one inch taller. The one with brown eyes and slightly shorter hair...what, you can't see his eyes? Uh...okay...the guy with the more athletic back...oh fuck it. The black guy."

Race exists. It's one more thing that makes us different. Some of us are taller than others. Some of us are fatter than others. Some of us are men, some are women. Some are old, some are little kids. We have different color hair. Big noses, small noses, big ears, small ears.

I can say, "Look at the short, fat, bald guy with big ears", and we're cool. But if I say, "Look at that black guy over there", the room gets quiet. It's stupid. People have different color skin, just like they have different color hair.