I too am a 'WM'. The law school I attend is 65% female and of those females 60% or more are non-'white'. I'm seeing a Sri Lankan girl who says that she cannot stand Sri Lankan men and would never see another. I've heard similar things from asian girls and even some middle eastern girls, in that they would never date within their own culture and much prefer white guys, indeed are even frustrated that white guys don't pay them enough attention. However, I don't think that this is necessarily a race thing in itself, but more a consequence of circumstances.
The main problem that I hear from these girls is the shortage of masculine men generally in academia and the professions. And by men I don't mean some 150 pound 5 foot bespectacled nerd. I just don't see that many guys of any race at all who are very masculine. The ones that are have to beat the girls off with a stick, at least in my circle.
Another thing worth considering is that in asia, from Thailand to India, paleness is an ideal. Girls from these countries find pale skin tone appealing in the same way that 'white' guys dig latinas with honey colored skin. Go into any supermarker or 7-11 in Thailand, Malaysia, Japan, Singapore, India or Sri Lanka and you'll find more skin-whitening products than we have skin-darkening products.
Granted, I'm in Australia, and we don't have as much of the black/white stuff that goes on in the States. But I think women's opinions are very much shaped by the media and those with less integrity will base their preferences on more superficial ideals than you might expect, and I think this is common to the US and Australia. Girls who are either foreign born or first generation find it appealing to date someone who matches what they see as the ideal in the popular media of the country they find themselves in, and combined with a shortage of men generally this has brought me many benefits. Masculinity in the media is basically 6 foot plus, big arms, 6 pack, a clean shave and a polo shirt. Which would be me if I was gay enough to wear the kind of polo shirts available here.
So while I can't comment on the black/white thing, I can add a perspective from my country as far as the second paragraph from the OP goes, vis a vis the non-white girls' preferred squeeze. Unfortunately I think there is something of truth in that sentiment.
However, the rest of the post is horsesh!t. Why do you want a white chick you freaking racist? Maybe the reason that girls 'of color' chase after white men is because racists like you aren't interested in anything except what conforms to your OC white girl fantasies? I find it hard to believe there isn't a plethora of attractive women of many cultures in your prospective graduate school. I've always slept with whatever takes my fancy regardless of skin tone, and some of the sweetest, least selfish, hottest girls I've been with have been 100% Indian, Japanese, Malaysian, Sri Lankan, and Sierra Leone..ian.
I have to admit, they've mostly had Aussie accents and been the ones with slightly more western facial features compared to their friends, sisters etc... Maybe I discriminate the same as you do. And they do seem to prefer white guys, which kind of makes me think they're a bit brainwashed by non-asian or non-african pop culture. But that's kind of the point... it's the girls that do the discriminating when it comes down to it. You might choose to not hit on some girls because they have skin like burnt sugar and you're a redneck, but if she came looking for some sugar in her bowl you'd be laying it down unless you were from Alabama or Queensland (Aussie equivalent) or something. Girls do the choosing and decide who sleeps with whom, and they usually have good, if occasionally semi-rational reasons for it.
The most ridiculous thing is racism in America. Your black and white and so on are all from the homogenised culture. You eat the same food and have the same cultural practices. I've been with girls whose parents were planning to arrange their marriages for them to some effeminate little misogynist from their own culture, girls who are the sole English speaker in their families, girls who would be severaly beaten or killed for sleeping with me, etc. I can understand cultural ignorance and bigotry if the bigot is a moron and the target of the bigotry has been in Australia about 10 secs but in the States, literally the only thing that divides your 'races' is skin color and socioeconomic trends that have nothing to do with cultural practices or differences and everything to do with the racism itself.
I suggest you broaden your horizons before you start wondering why woman aren't broadening theirs.