I'm white, I use the word "******" with my friends, both black and white. Why? I'm not trying to be offensive when I say it. Word are just sounds with associated meanings and I find the associated meaning with the word ****** pointless. Yes, it used to be racially charged, still is to some extent. Like all other words that have negative usages, unless it is being used to be offensive, it's not. That and the black American (not African-American unless they have lived in Africa) community has allowed it, to some extent, persist as a normally accepted word.
The Longs Story Short: It's only offensive when it's meant to be offensive, just like all the other racial "slurs"