How can we get Asians to have Western forces with dissent?
A: easy - just have more tech complexity. For instance, New Model armies for China can require use of added techs to obtain, making it more imperative for factions like China to tech further while Westerners don't need to do so.
Blood and Soil is a good tech to use, esp to promote Industrial Era units. So for China, Blood and Soil is necessary to recruit new model army units, while for Japan it is a prerequisite for its marine corps.