There is a very simple answer to why this is. Asian men are no longer raised as men. The term "Momma's Boy" is no where more true than in asian countries like China, Korea, and Japan.
Birth rates are down, so the increased importance of having a male son in the family is paramount which unfortunately leads to an over protective matriarchal society that pampers and babies the sons, and especially the first born son. Most boys don't do anything while growing up. They don't clean up after themselves, they don't cook, do dishes, house chores. Their sole goal in life is to study and get into a competitive college. So most boys are pretty helpless and can't even wash themselves in most situations cause their mom's bath them.
The only man training they get is when they have to do military service. Where for the first time, their mom's are no longer there. They bond with other boys raised the same way and they live for the next couple years under a male cast system. They come out being a bit more self sufficient, but when they get out, their mom's are right there to pick up after them again.
So most women don't have true "male" figures to date. Basically at a time when their hormones are raging and want someone to look up to, they meet a guy, mostly through social introductions via family or match making services, only to meet a guy they have to take care of like a baby, when they aren't even ready for motherhood. For some women, this is fine and they go right on babying their boyfriends to earn the respect of the boy's mother who pays an important part in whether they get married or not. Especially if the boy is from an influential family with money.
Asian boys are extremely effeminate. Just look at the models and pop singers in japan and korea today. They look like girls.
I think women in general, want a strong alpha male type and its really really difficult to find them in asia today. So more independent women who want a career or to do something other than being a housewife will seek out white guys. First, because dating a brown or black is beneath them. Whites are the next best choice. White guys compared to asian boys are more manly than asian momma's boys.
I can see how this is looked at by a socially awkward asian boy as being a traitor because they were brought up to be worshipped for being just male with no other redeeming characters, except maybe they got into one of the top colleges.
I think the culture has manifested itself into a natural reaction from the boys as "why the fuck aren't you marrying me, and instead being a race traitor" which really is not that much different from american feminists point of view of men where they want every man to worship them but instead are aghast that no men like fat, slutty, bitches that have no manners. Asian men are the epitome of the male feminist with the same irrational logic.