Putting the accuracy of this statement aside, I find this irrelevant. Language evolves, Crow. Words change. Gay, bitch and faggot are other controversial terms with contemporary usage defined by what they mean today and not historically, or by what other words they're derivative of. You know this, I am sure, which is why I don't understand your disconnect when it comes to nigger/nigga.
This hasn't been my experience, and even if it had: So what? What I choose to say or not say will not be governed by the actions of racists.
Someone who isn't black using either word is going to be controversial, as this thread highlights. Regardless, "nigga" is a term of endearment and a casual form of address lacking the stark negative connotation and sting of nigger, by design. You keep insisting otherwise, and that is perhaps the problem I have with your posts. It feels as if you're attempting to dictate the definition of terms used by and amongst people in a culture you are not a part of. But you can't.