The first comic I ever read with him when I was a kid was an issue of Batman and the Outsiders, and maybe this sounds naive, but I saw that his lightning bolts were black, and I thought "Oh, that must be why they call him Black Lightning!" Like it was the only possible explanation, and not the dated reference to his race that flew more or less over my head.
So... I like that. I imagine that early in his days as a crime fighter, someone said "He shoots black lightning from his hands!" and it got picked up by the news outlets, that kind of thing, haha!