Earlier quoted context omitted.
Well it just so happens I am black and I've been using the word most of my life. Nigga is just "bro" or "dude" but exclusively used among black/minority communities. I realize the word nigga is A Big Deal for white people but really in our community it is used as casually as the word "like" in any given sentence. Interestingly I have even used it with black bosses before in a joking casual way.
You're ignoring the fact that a non-negligible percentage of black people don't want to be called any version of "nigga" by anybody, including other black people. The same is not even remotely true of bro or dude
It's so common people joke about it "don't call me dude, bro | don't call me bro, pal" etc etc