I guess it's very often the case for most people that we tend to crave and want something badly especially if it is something that they can't have. It's rather difficult to generalize this because I've known some Asian guys who are very into white women just like your friend, but at the same time I've also known plenty of others who just aren't interested by the idea at all. I'm studying in Sweden at the moment, so I've been asking the other Asian male students this question. I've heard some Westerners mentioning that Asians (with Chinese being the majority here) like to stick together and don't interact with others. So it's either they don't care about it or are secretly obsessing about white women, hahaha
Speaking for myself, I am keen to experiment and try it with Western women. In terms of looks they are exotic for me because features like blond/brown hair and the combination of blue or green eyes do not exist in Asian women (unless of course they dye their hair or wear color contact lenses, which I do not like at all). I generally prefer taller women (most Asian guys do not). By taller, I don't necessarily mean taller than me, but I like it especially if a girl is 170cm or above, which is rare and hard to find among Asian girls (when I do find some, my interest peaks). It's pretty common to find cute girls of that height here in Sweden where the general population is more on the tall side. So if any of you are just thinking that just because I am Asian, I must have a blonde fetish and would go for anybody as long as she's just white and blond, then you're making a false assumption here. FYI, I'm not into thick girls with big hips and thighs that wear short pants up to their asses to show off their cellulite (somehow that is seen pretty often during the summer here. It's none of my business what they wear, but I've got to say that they sure have a lot of confidence).
I guess that with the movies/magazines featuring a lot of Western women as "attractive" could have a lot of influence too. But generally, I believe that every race has their share of attractive women. It all comes down to facial symmetry and body shape. That's just the physical aspect we're talking about.
In terms of cultural compatibility though, I would say it's difficult. Unless we're speaking about a Westernized Asian person who grew up in the West, most Asian guys who are really Asian would definitely find that the cultures and way of thinking/mentality are totally different and this is the most difficult thing if one were to choose to pursue a relationship. As most of the time, it will most likely be the guy who has to adapt.
In my own opinion, I do find that Thai girls are more gentle and sweeter (I guess I haven't managed to attract any white girls enough for her to show off her sweet side). Even the Thai girls, who are friends, are more sweeter than the girls here who are friends (in general). The downside though is that they are pretty materialistic and I could say that goes for the society as a whole in general. Well, everybody wants security in life. Our values have changed a lot and I believe it's an irreversible trend now. I don't really get the feeling that the Swedish girls here are that materialistic and that's what I like (I believe that it's probably a different story in the US). Sweden is said to be one of the most egalitarian societies on earth and I guess with a welfare state that lessens a lot of the parents' burden (no tuition fees all the way to university level, student loans for every citizen, free lunch at school up to the end of high school, subsidized healthcare (not completely free)), most women will probably don't have to worry too much whether a man is super rich or not, he just needs to be able to support himself.