It's strange, because I had the same thoughts about the new Grand Theft Auto game which focuses on Chinese characters.
My feeling is that if you're just using "Othered" characters/cultures just for the sake of window dressing, then it becomes appropriation. The most obvious real life example would be the kanji/hanzi tattoo.
And yeah, Firefly didn't last long... but there really was no reason that they needed to bother including this hybrid culture in the first place. It really seemed like a "neat idea" that they had but then never got around to developing... so all we get is a flag that's half American-half Chinese and some random Mandarin/Cantonese thrown around.
Just for shits and giggles - what's a good example of using Chinese in a SF series?
Space Above and Beyond. In one of final episodes, the President gives a televised speech to the world and it is subtitled in Chinese. It was a nice touch and didn't feel as contrived as Firefly.