[In this essay, 'Westerner' and 'American' are cultural (not racial) terms, as is 'Asian'. People who are culturally Western are 'Westerners', regardless of race, and people who are culturally Asian are 'Asians', regardless of race.]
I find it very interesting to read the article Ugly white men adored in Japan, which describes how white North American men with ugly characters and poor personalities are treated like gods in Asia. I'm not sure if the issue is totally racial. I believe there is a cultural component to it. Let me share my perceptions on the issue. I don't have answers, but I can offer some possible explanations.
I've been studying Japanese for a while. My teacher doesn't just teach grammar, but also social skills. She repeatedly emphasized to the class that when someone is talking, it is very important to give the other person some indication that you are actively listening, such as making statements of assent. One thing I noticed about Chinese and Japanese culture is that reciprocity is very important, and even if people are not interested in what you're saying, they generally listen politely and attentively. If you don't know better, you may even be convinced they are enjoying the conversation. I have limited exposure to other Asian cultures, but I have a number of Thai friends, and their behavior as far as listening is concerned, does not seem out of sync with Chinese and Japanese norms.
Western culture places importance on being a good, respectful listener too, but it is not too uncommon for Americans, at least, to show their boredom openly on their faces if someone is talking about something they're not interested in. But Chinese and Japanese rarely show their disinterest so blatantly.
I've noticed that a significant number of American men (race not necessarily relevant) who date Asia-born women are very gabby men who like to show off their pseudo-intellectualism. Fellow Americans do not put up with their BS, so the "good listener" attribute of Asians comes in handy. Here are a couple of examples, both of whom happen to be white Americans (but the issue here is culture, not race. Any culturally American indiviual could be in the same role):
R, an Irish American, thinks Americans are 'stupid' - he likes to talk about high-tech topics and spout unnecessarily complicated language. R is only interested in befriending Asians from Asia. R has no interest in befriending Asian Americans, or Asians of other nationalities for whom English is a first language. Not a wonder - his pretentious pseudo-intellectual babble can only deceive those who have a limited command of English. In addition, Americans of any race generally have a much shorter fuse when it comes to egotistic, pretentious behavior than persons raised in some Asian cultures.
K, a German American man, is dating a Thai woman. He has passed culturally insensitive and chauvinistic remarks in her presence on more than one occasion, but yet she did not leave him. Southeast Asians are generally less confrontational than Westerners (not making a value judgement about whether 'confrontational' is good or bad here), so in a situation where an American would have jumped on a questionable statement right away, an Asian would sometimes bear the insult in silence. And that was what she did. She did not confront him immediately, but only did so much later at the encouragement of her friends.
In his 'deep' conversation, K often uses fancy words that his girlfriend doesn't understand. Often, she has to turn to other native English speakers in his absence to explain what her boyfriend is saying. She is unwilling to let him know how little she understands him because she does not want to be constantly interrupting the conversation. Even fellow native English speakers, who do understand his 'fancy' words, find him eager to appear knowledgeable and intellectual. He likes to talk about artsy, 'cultural' topics, about books he read or foreign movies he saw. But when someone talks about a topic that K knows nothing about, such as West African history, K gets very defensive and tries to put the speaker down. He snorts derisively, rolls his eyes, and puts on an expression of scorn and superiority on his face. He tries to dismiss the perceived expertise of others who don't even have any intention of showing him up or putting him down.
This might be the case of yet another reject who is shunned by fellow Americans and who tries to stroke his ego with the company of unsuspecting Asians. Even his girlfriend admits that he is highly insecure and extremely sensitive about anyone thinking he is stupid. So she asks her friends not to point out his mistakes or jump on any inaccurate statements he makes for fear of hurting his feelings.
It is probably not too far-fetched to say that both men described above are highly insecure individuals who are intimidated by anyone who knows more about anything than they do. (Well, most of us know everything about anything - there probably are billions of people who know more than us on a given subject matter. And most people don't find that threatening or scary.) And such are the individuals who deliberately seek out the company of Asians, and Asian women in particular.
Both white men mentioned above enjoy playing the role of "teacher" to immigrant friends. It boosts their ego to play "great white guide" to a newcomer trying to find her way around American society. Both men claim to be interested in 'foreign culture', but they do not venture beyond superficial activities like dating women, watching movies and eating 'exotic' food. The exchange is basically a one way street, with the Western man droning on endlessly about his intellect and his achievements, and the Asian woman not getting to talk as much in return. Such men like it this way.
Another cultural attribute that inadvertently works to put individual Westerners on a higher pedestal in the eyes of Asians is traditional Asian modesty about one's achievements. Let's assume there is an 'objective' scale on which we can rate an individual's achievement in a certain area. And let's say there are 2 individuals - one Asian, one American - who have achieved a rating of 5 out of 10 on this 'objective' scale for an unspecified area of expertise. The American usually makes his achievements sound a little grander, so he rates himself at 7. The Asian, bound by modesty, rates himself at 3. The mentality is, "If I'm truly good, people would notice. My actions will speak louder than words." But guess what, most people are lazy, or don't have the chance to know you better, and don't look beneath the surface.
So you've 2 individuals of equal achievement, but they present their achievements differently in person, and on their resumes. Who is at the advantage? You decide. One of my Chinese friends is always complaining that one of his best friends, also Chinese, does not compete effectively with Americans when it comes to job searching, because he is so disinclined to 'boast' about his achievements on his resume.
And likewise, when it comes to wooing women, the man who sells his positives more aggressively has the initial advantage. And sometimes, the initial advantage makes all the difference. Asian women, who are used to a more stringent self-rating system, would think that the American who claims he is a 7 is actually a 9, when he is really a 5. And the Asian man, modestly rating himself at 3, might be perceived by the Asian woman as a 5, but how can he compete against the American man who is perceived to be a 9 (even though he is really a 5)?
Just my humble effort at explaining the intermarriage gap from the 'cultural' point of view, since we've already heard the arguments about racial preferences (aka "white is right") driving intermarriage trends.