Saying something like "racial slurs" could potentially leave one wondering if this was something relatively mild, possibly even a mere misunderstanding that was blown out of proportion. Mentioning that someone dropped an n-bomb leaves no room for uncertainty.

It's like "sexual harassment." That phrase alone will have some people thinking "oh, the poor guy just said she looked nice today and she flipped out." If you say "he stuck his hand up her dress and told her to be at his apartment at 9pm," there's no space for that sort of misunderstanding.

It's a style figure; i.e. a choice an author makes, in order to convey their intent most clearly. It's artistic freedom to choose whether or not to use it. I don't see what purpose your insistence on delineated rules on when to use what words serves. I for one found the article more authentic in the way it was written, vs if they would have used 'racial slurs' or another generic term.