To tell you honestly since I live with such a majority who are white, black, blue, and green I see it more as cultural differences rather than skin color. For example, I'm dark skinned (never called myself black; didn't viewpoint) but grew up in a white locality. I moved here and people of African american descent or they say black tell me, "you're not from here are you?" and we go into a conversation of my not being raised in Black Culture (lack of better words). There is a different language, customs, beliefs, and way of life shared by one locality than another. South Eastern U.S. totally different, yet we all have the same skin tone and we "get it." Probably because of history...
Another reason black is better than ethnicity say African american to many people is the differentiation between community and culture and politically correct terms the "white" people gave us. I mean, I looked on my family genealogy and on their birth certificate, they have negro.
A lot of what makes black and white people different is the language, culture, and customs. However, we have similar history but because of our roles and family family roles, unless we are militants, travel, or raised elsewhere, there's a sense of them vs. they. A lot of times black and white are used many of us don't even know where we came from specifically.
Political issues more than anything else.