I think you're missing my point. Rappers, etc. use all the curse words they can on purpose. Its part of their "schtick." I'm talking about plain-old everyday discourse.
Oh, sorry. I thought when you said "culture" you meant culture. But you mean everyday discourse, as in what I hear people say in person? Even then I'd say "dick" and "bitch" are at least equally common.
I don't think most people who find the c-word or n-word heinous speech are thinking "that person shouldn't be using such offensive language against these poor, oppressed people."
That's pretty close to exactly what they're thinking. Oh, they wouldn't say "poor, oppressed," maybe. How about "disadvantaged" or "less privileged" or maybe they'd just say the name of the group itself: black people, women, gay people. Whatever you like.
The point is, slurs used to insult those groups carry more power to hurt and offend than slurs used against dominant groups. As a member of two out of of those three dominant groups, I can attest that I'm not particularly stung by "honky" or "breeder," nor have I known any other members of those groups who were. They're more like, "Yeah, OK, fair is fair, there should be some insulting term for the other side." But in practice, they just aren't as insulting.