I think you nailed it when you described ebony skin as a fashion choice, and looked at that way, it's kinda neat.

I don't see blackface there, all examples of which that I've seen involved cartoonish lipstick and white circles around the eyes. The dye job in the photo looks comprehensive and the shade is natural African, not unnatural black; and the goal is clearly an aesthetic effect (not that I think they achieved it, it still looks a little off, but the intent is clear).

Women change their skin color every time they apply "blush" and any other cosmetic with coloring agents. Ebony is a larger excursion, but so? I've learned to keep my mouth shut about women's fashions, and this case is no different. If that's what they want, that's what they'll wear.