It seems to be gaining in popularity here in the States nowadays (with Asian guys and white women), but it's still not nearly as common as Asian women with white guys. My guess is that it all goes back to how women of any nationality wants to feel safe and protected by her man. And unfortunately height is recognized as being a contributor to one's ability to provide security...so Asians who tend to be shorter in height often get overlooked...
Either that or they've subscribed to the stereotype that we Asians pack tiny pistols.