I personally think that it's more about our unfamiliarity with Asian masculine and feminine traits and we more easily mistake their features as feminine. My guess is that it's obvious to them in their culture as it is here and that they would have to really work at it or even do HRT to get a passable face.
On that note, I've often wondered if we appear more feminine to them than their males do? For example, these exceptionally tall women don't really look that far off from some of us as their features are more exaggeratedly male just due to their height:
