Because Asian women are substantially thinner than their white counterparts, it is only natural that their overall desirability would increase.
More importantly, when considering marriage, men have two great fears.
In the past, when there were many fewer overweight white women, a man would just marry a thin white girl.
When Caucasian men marry Asian women, the couple is twice as likely to both be college educated and will make on average 20% more money than a white-white couple.
Sociologists talk about all sorts of possible explanations: the desire of Asians to assimilate, the increasing acceptance of interracial marriage, the sexualization of Asian women as docile and subservient, the smaller penises of Asian men. I’m reminded of an old joke which explains the phenomenon of Asian women marrying white guys: Why does a dog lick its genitals? In our society, whites are at the top of the social ladder and people naturally want to marry up.