I don't think that it is a fact that black women are more curvacious, however they are on the whole more comfortable with their larger assets due to upbringing and general sterotyping. It is a difference in bone structure, more than anything else.
To roughly quote 'Scrubs' -
quote:
J.D - What is the difference between a black woman and a white woman?
Turk - When a black woman asks if her ass looks big you answer HELL YEAH!
Again, I don't believe there is a more call for black dominias or submissives, just a more vocal response due to a particular fetish and preference, in the same way long hair is liked, or a particular hair colour, eye colour, height etc... But the self acceptance tends to be there, from my experience.
Peace
the.dark.