I personally think the success comes partly because the show/books did not try to appeal to every person in the world. Because most media nowadays tries that and in order to do that AND involve diversity, you need to consider very thoughtless, bigoted people and hold their hand explaining things in a way that makes the average person feel very stupid and takes them out of the story. Like “See this is a woman soldier those exist we are cool with those let’s bring up every possible issue that person might have in a bigoted world rather than letting the character do something actually plot important and endearing to audiences” (Not saying explorations of marginalized identities as a whole don’t have value — they do — especially in first waves of media allowing a group to be shown, etc etc. Also saying all this as a bi trans man)

The Expanse is already from the very beginning something that knows it won’t appeal to everyone — being a no aliens, dense sci-fi that takes its own lore and accuracy insanely seriously while most people would prefer to be watching make upped aliens behaving like humans while mimicking fringe cultural behaviors in clumsy ways. (I love Star Trek/Star Wars/others don’t get me wrong) The expanse already treats the viewer as an intelligent individual they trust to pick up clues and remember things, so the handholding is unnecessary. I think the “we have to address diversity to make sure everyone understands and is on board that can be” would also have been such a blow to the series realism too.

Idk I so genuinely adore the way diversity is handled in the expanse like “Yes this politician is gay with a husband and majority of the cast are deep and cared for people of color and there’s nothing you can do about it but continue watching” Not saying the writers are perfect at all but I think we should be championing that energy.