I believe it also has to do with the inherent shyness that comes from their culture. Their small size, combined with that shyness, gives them a little girl quality that men find attractive: to want to put their arm around her and protect her.
Another thing is how the Asian women age. To look at one, you can't tell if they're 16, 26, or 36. After 40, it's also a crap shoot.
This is the best I can do. It's like trying to explain the color blue to a person that has been blind from birth.
Caption this Meme 