Why do hobgoblins look like chinese?
I think goblinoid hordes (also orcs and gobbos) have often been depicted as similar to mongols, very often even as tribes inhabiting eastern areas of the given world, from where they pour forth. Especially GW did this a lot, the fur-brimmed helmet/cap being a common trait on earlier sculpts.
I don't see any other particular reason - and I also would prefer hobgoblins in a more rag-tag generic fantasy style.
I must say, I don't like these a lot. Nothing overall wrong with the quality of the sculpts, but they strike me more as some kind of pulp lost world/retro sci-fi race than a kind of goblinoids (and it's not because of the skin colour). Not my cup of tea.