I'm a huge fan of interracial porn (but only WW / BM), but ten years ago there wasn't much (well to my mind), around then. Why has it suddenly become one of the most popular genres of porn, why do you think that is?
I suspect people process toxic culture in part through sex. The white women with black men phenomena in particular is almost certainly leveraging the racist perception of black hyper-masculinity and is thus related to cuckoldry.
The forbidden fruit taboo. Notice no noise is made about Asian male/white woman or non-black Latino male/white woman porn.
Notice BW/WM porn is never really categorized as interracial. There isn't a strong taboo.
Black women almost always seem to be paired off with white men, but a big deal is made when black men pairs with a white woman--then they label it BBC. It's crazy.
I haven't noticed much of an increase, but then I've been an addict since i was a child. All different kinds, so I suspect it might be Conformation Bias. you're more actively looking for it, so finding it easier to find. Blacks on Blonds/Dogfart has been around since the 90s.
It's pretty obviously the Size myth. Not that black men can't, on average have larger phalli, but that penis size has anything to do with sexual prowess. (Also, on average. They can be larger, but it's not reliable unless you check.) i notice they're typically petite-to-tiny white chicks, and the photography/cinematography is specifically to emphasize the size disparity.
Realistically, all a monster cock means is more foreplay. So, if you don't like foreplay, and you aren't into hurting her, then you don't really want a monster cock. it's a lot more work on your part. (I happen to like foreplay better than sex.)