Ancient Chinese customs (including clothing styles) probably died after the Ming Dynasty was taken over by the Qing Dynasty – the Qing Dynasty was a Manchurian led dynasty that forced Manchurian customs and habits on its people.
But it was really the ending of the Qing Dynasty, the establishment of the ROC and finally the PRC, who finally did away with a lot of old Chinese customs, traditions and religions. The PRC, being a communist party, wanted to eliminate all the bourgeois and old imperial influence, purged a lot of Confucian and religious traditions and destroyed many temples and artifacts during the Cultural Revolution.
Japan and Korea and to a lesser extent Taiwan have never suffered such massive changes (revolutions) to their government.
I’m glad that I’m not the only one who traveled to Korea, Japan and Taiwan, and then back to China and thought “damn, why does Korea/Japan/Taiwan seem more traditionally Chinese than China does?” I think its the deep Confucian culture influence that still lingers in Japan/Korea/Taiwan (but less so in China) that is a big factor