because that is what upset the Chinese players/government: Chinese pandas in Japanese clothing. Samwise realized his mistake and started drawing Panderan in proper Chinese clothing.
Maybe they'll turn them into Furbolgs or some other bear like race from the Wow-lore. After all, it wouldn't be the first time chinese wow gets this kind of treatment because of their government deem it unfit for their citizens.
Didn't Samwise sketch out a Chinese panda years (2003?) before Kung Fu panda came out in 2008? It might have even been the inspiration for the movie, heh... Haven't WoW nerds been crying for a Pandarian race since WoW was in Alpha?