It's an ugly word, no matter whose mouth it comes out of or for what purpose.
It's one of many ugly words used to describe certain ethnicities but it gets ALL of the attention.
Why?
There's nothing ugly about a word.
True, but in an attempt to avoid that word, several similar sounding words have practically vanished from our language.
A story was posted a while back in which a teacher, in discussing a book the class was reading(I believe) used the word niggardly to describe a character, which means selfish. The class, needless to say had no clue and reacted instinctively by going ballistic. The parents , also apparently ignorant, went ballistic as well. The teacher wound up either getting suspended or fired, all for the use of a word whose meaning used to be commonly known.
The term 'black' to me is the same as the term 'white'. They're too inclusive. I grew up referring to black people as Negro, but that is too similar to 'the N word' for some people's taste. I've gotten some VERY hard looks before their brain kicks in and they realize what I've said.
Bill Cosby mentioned it and blacks laughed. If a white guy said the same word, he'd be lynched. I'd take blacks' claim its offensive a lot more seriously if they expurged it from THEIR vocabulary. An ugly word ought to be bleeped out of social conversation no matter the circumstances.