Andrew Green said:The do-gi, Kano's creation, was not.
It was designed specifically for training as I understand it, created white because dye's where expensive. Everyone wearing the same gi was a way to remove "class" from training, no fancy clothes vs peasant clothes.
Now it may resemble clothes worn at the time, which makes sense. But, the do-gi was created specifically for Judo, then adapted to karate.
Kano eventually started having his yudansha where black belts to distinguish them, not because there belts got dirty.
Well, kimonos were often worn during martial arts training prior to the modern era. During more intense periods of training, the participants would often strip down to their undergarments. Judo, with it emphasis on competitive practice, meant that few wore their kimonos because of the heat. The fact that it was easier to grip a kimono than undergarments meant that it was a futher disadvantage. Kano eventually decided that training in underwear was A) not promoting the image he wanted as a gentleman's art B) not standardized and C) resulting in frequently damaged clothes. He created a standardized stronger version of traditional undergarments - the Gi.
I have heard the "class warfare" theory debunked many times. Kano made a point of trying to recruit the social elite and did not take steps to make the poor feel more comfortable in his training hall - it's hardly the reason for the gi. There are more extensive discussions of this elsewhere.
Kano's BBs were used to distinguish those who were qualified to correct technique from those who had not yet proven such a capability to him - most his BBs were from JJJ schools rather than promoted within the Judo framework.
Colored belts came into being in France - it a matter of some debate as to who origionally came up with the idea, but they ranked judo students competitive prowess and later other things. From there it spread back to Japan and was eventually standardized.
The Karate gi comes from the Judo gi because Funakoshi's classes had many Judoka, who wore their gi in an attempt to distinguish themselves from non-judoists in the karate class. Eventually, seeking to standardize apparel, Funakoshi told all his students to buy judo gi. The belts spread in a similar manner. The karate gi has changed little, while to some extent the judo gi has evolved, but thats a whole new thread.