Well Trust like I said, if you get offended by the slurs, then I think you should try and make people notice and care about it. It is horrible that white people are called that, and if you are, I'm terribly sorry. And btw, you're generalizing again. You have no idea whether every single black person who has been called a nigger has called anyone else a racial slur. These people retaliated with a racial slur because a racial slur was used against them. I'm definitely not calling it right, but you have to understand that two wrongs don't make a right unless you're Chuck Norris, and that whatever the black people say, Michael Richards still said some pretty offensive things.
And deadly, I think you might have misinterpreted what I said. If you are seriously insulted by them, then yes, sue. Although personally I think anyone suing over being called anything is pretty stupid.