Historical reasons, black Americans don't want white Americans to use the word anymore.
I'm sure any Africans being held by Arabs against their will right now will hold the same type of sentiments for them in the future.
...And people are not being taken out of Africa today for slavery on a large scale like the transatlantic slave trade that occurred centuries ago, even though there is modern forms of slavery, like forced labor and human trafficking, with Africans being exploited within their own countries or transported to neighboring nations.
BUT it is all Illegal and condemned, unlike back in the day.