I understand where you're coming from but I think in reality it's generally very difficult to just "eliminate" a word. It's actually easier to just change the social rules around using that word to apply to different people.
And when you think about it, if you've "eliminated" a word like the n word and a black person hears two people utter this word, one white and one black, it's only natural he would be more offended by the white person saying it as in our country's history whites were the ones who owned slaves. Not blacks.
Just like a woman would be more offended if a man called her a b word because historically men held more power and generally exercised that power over women, whereas another woman saying might be offensive, but not AS offensive.
So these divisions of power over these words arise rather naturally in my opinion, because of the history of the word's use.
Another argument is you can't just ignore centuries of history and state: "okay starting now, we're all equal." Partially because that is just a gross shifting of responsibility for those who enjoyed power in the past, and because history helps us identify the causes of imbalances in power in today's society. Especially those imbalances that are hard to see even for those at the lower end of it. ("The frog doesn't notice you're boiling him if you very gradually turn up the heat", and all.)