Umm, I'm asian, and I've dated some white guys (no racism intended, I'm use to calling them that, it's easier for me), my reasons are that they are more open to exploration and I have a curious nature that likes to explore
, they seems to be more open about sexuality and what not. For instance if you go and tell a white guy that you have a one night stand before, he'll probably be like its pretty common here, while if you tell an asian guy he'll assume your a slut already and probably wouldnt want to be lay a finger on you.
But aside from that I think your hypotheses are generalizing such a board subject, since everyone have their own different reasons of dating before even thinking of the technical things like racials differences.For example, some of the answers recieved from the girls you inquire to "why they date white guys" could be what they really mean, that its the personallity that attracts, is that hard to believe?