Well modern culture praises blacks because they look cool and trendy while promoting diversity increasing population sizes by importing child factories. They build muscles faster and their dick sizes are slightly above average. If it would fool anyone by coloring yourself and while at the same time playing the victim card that would be easy install payments.
Other than that, probably to be around people that are black or are minorities and have an easier time "fitting in" even though good luck with that. Black is also seen as the extreme end of exotic as anon pointed out, so for some people being an oogabooga is unusually attractive if you have the fetish provided.
Luckily for us, people like this are nearly 100% of the time are not very bright and are stuck dealing with their newly made up race problems for the rest of their lives, scientifically speaking.