Some good looking black men just like big women because they like curves. In some African tribes and in(some countries) Europe, a big woman is considered beautiful. I don't think it is a case of self-hate. It is a case of a man and woman who know and are attracted to each other. I have seen many couples like this all the time in many variations. We don't know why they are together, but they are. No one knows why. You cannot help whom you are attracted to.
I think there is a difference from the idea of weight a while back and more recently. Heavier women may have been regarded in a better light because it signaled that they were well-off, but I don't think that's the case so much anymore.
Moreover, I believe there are big differences in what people perceive as curvy, thick, voluptuous. Personally, curvy to me comes before thick and voluptuous. If your checking out woman from a side profile, she'll have curvature in the spine (poking her butt out) as well as "booty meat" to substantiate her qualifications as "having an ass" or a "big butt".
While her butt is usually a bit more 3d than her counter parts, her thighs maintain a slimmer proportion, thus giving the butt a larger appearance also (some men like the thigh bigger as well, which I believe to be the "Rhino leg").
Lastly, waist and hips. Maybe not important on their own, but lumped with this ass theory, becomes very important. The waist must cinch in. For instance, if you take a west from a "skinny" girl, and replace it with that of a "heavier" girl, the heavy girls ass is going to stick out because the proportion there ("Cocola bottle effect/hourglass figure). The smaller waist is naturally going to give flare to the hips. If the hips run into the slimmer thigh, the visual effect will be more vast (better imho). The hips also, from a front or back view, will not be squared off (much like SpongeBob square pants), again, adding onto the hourglass figure.
Obviously some race/ethnicities may generally have more or less women in the hourglass range, but they exist in any race/ethnicity. I believe many people enjoy curves from the waist down, some don't surprisingly to me. So no matter what race/ethnity I'm looking at, I'm looking for curves, and If I find them outside of the AAW (whom seem to possess them a lot more), man am I excited. A white girl with curves for me, is, is, I could go on, I just luv em' a lot lol.
My example would be opposite ends of the spectrum:
Hourglass, Big Ass: Beyonce (Singer-Entertainer)
vs.
SpongeBob, No Ass: Jennifer Carpenter (Actress from Dexter)