I am not an expert in gender-related subject, but according to my observation, there can be two major reasons behind this phenomenon:
1) Loads of Asian males are expected to inherit the family business and/or “have a real job.” It is truly difficult to be an aspiring male artist in a non-artistic family, unless one has exceptional parents who are interested in the boy(s)’s true happiness.
2) It is easier to sell body images as females in the music business. In other words, men cannot play a serious concert half naked or dress “too creatively" on the stage, but for women it is accepted and even encouraged.
So there is not much to be proud of the fact there are more female musicians in Asia. For me it was a result of patriarchy anyway.