A:
When
Grandmaster Ie fled to Indonesia it was a time of severe persecution for Chinese people in Indonesia. Chinese weren't allowed to use chopsticks, have Chinese names or practice Chinese martial arts. In order to fool the authorities, Grandmaster Ie called the art "Shao-lin Do", and dressed his students in Japanese uniforms, and thus was able to teach the art. We continue to wear the Japanese uniforms not merely for their durable affordability, but also to remember how close our art came to dying in the last hundred years. Were it not for Grandmaster Ie's ingenuity in disguising the Shao-lin art, we would have nothing to study today.
In addition, the Japanese style uniform is virtually identical to what the monks wore when training (crossed tops, loose pants and colored belts to denote rank), according to historical resources like the surviving frescoes of the martial monks training from the Thousand Buddha Hall at the original Shao-lin temple. The frog button silky uniform that people often associate with Kung Fu is actually a relatively recent innovation, dating to the late Ching dynasty. Hence these fancier types of uniforms are both less historically accurate, and also ill-suited to the intensity of traditional Shao-lin training.