I even didn’t know this fetish existed in porn, but according to my personal experience in real life I very well witnessed that some, if not a lot of ethnic girls are more than willing to have sex with an attractive white guy and even more than that (relationship, having a family, children, the full program).
Usually the term interracial most often means black guy(s) and white woman in porn. It’s like 90 % of interracial porn. The reality is different of course, because many Asian, Latin and also Black women (next to the majority of white women as well) actually are attracted to handsome white men with a decent job, who can provide for a family (not the beer belly old fucks roaming South East Asia for cheap and unfortunately also most often underage Asian hookers).
The whole interracial category in porn got racist stereotypes and is mostly a sub-category of the humiliation fetish. It wouldn’t work at all, if white phenotypes wouldn’t be considered to be desirable. Since they are, a white woman fucking blacks is automatically humiliated, even more so, if she seemingly enjoys it. That’s the whole psychology behind this fetish, it’s about humiliation and degrading. It wouldn’t work otherwise. By the way white porn actresses doing interracial porn get payed extra. It's true.
White guy on ethnic girls doesn’t work like this, because it’s not about humiliation and degrading. Therefore it isn't common in porn, but in real life.
It’s porn after all. Nothing is realistic concerning porn, we all know that, but still consume it. All of the actors are in it for the money and that’s it. The sex displayed in porn isn’t realistic, because most of these positions on screen aren’t comfortable at all for the ones performing them and most people won’t be able to have an orgasm like this. Porn also works with fake sperm for cumshots and all the moaning and orgasms are usually fake! Just ask yourself, could you really enjoy it, if a full camera team surrounds you and a director gives your orders what and how to do now and when? “Cut! This performance was shit, do it again, like this or that…. Come on man, don’t slow down, what the fuck is this, do her properly and now lift her up and fuck her against the wall! WTF?! CUUUUT!! And now Again… And you girl, lift your legs, damn it and moan more loudly!” It’s work after all and actors get payed for it.
Anyway, while blacks on white or Asian women aren't seen as offensive in porn, despite all the absurd bullshit being said and made up in such flicks, why not also having it the other way around? Anyone finding the op's proposal offensive is a hypocrite, if he doesn't find absurd "black cock addiction" fantasies just as much offensive.