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 “Shaolin Do”, and dressed his students in Japanese uniforms, and thus was able to teach the art. We continue to wear the Japanese uniforms today both for their durable affordability, and as a reminder of how close our art came to dying in the last hundred years.
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). Historical resources such as the frescoes from the Thousand Buddha Hall at the original Shaolin temple show this in their depictions of the martial monks training. 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 ill-suited to the intensity of traditional Shaolin training.