The Expanse isn't generic, I totally agree, but what makes it distinctive isn't stuff like how individual combat works in that setting (unlike, say, Dune with its shields and so on), which is fairly generic assault rifles and squad combat stuff, or how big the interiors of ships/space stations are, but rather the worldbuilding and tone. If we completely ignored worldbuilding and tone, I think it would be hard to distinguish very large sections of The Expanse novels and TV series (I only read the first two novels, but watched the whole of the show) from most "space opera" in general apart from the lack of aliens, and if we ignore that also as worldbuilding, then a ton of what happens in The Expanse could happen in Mass Effect or Killjoys or whatever.
But the worldbuilding and tone are distinctive - it's basically "Game of Thrones In Spaaaaaaaaaaaaace" (minus incest), with the distant threat of the White Walkers being replaced by the weirdness/threat of the protomolecule, and I don't mean that as a dismissal or something (though half of SA Corey is the guy most likely to finish ASoIaF unless GRRM specifically no-one should, and close friends with GRRM - Daniel Abraham), just to say that a sort of backstabby, clawing, often amoral politics is centered in way even B5 and DS9 never did (esp. as conflicts are often within factions), and there are a lot of conspiracies and evil experiments and warcrimes going on (again, in a way that's rather more extreme than general space opera-y SF). Tonally it's usually pretty dark - the focus is on societal ills, most of the characters have something profoundly wrong with them or missing from them (even if they're good people - perhaps especially so), and so on. It's not a million miles from ME (they're both occupying a space with elements of "military SF" and "space opera" genres), but it's also not the same.
I will say, we don't see in this trailer much of that politics/tone, though there are asides about them, and I expect we'll see later trailers that make that more of a thing. Based on Owlcat's other games, especially Rogue Trader, I think the politics, warcrimes, etc. will probably be pretty important. So I agree that the trailer isn't distinctively The Expanse but I guess my issue is that I don't see anything that disqualifies it from being The Expanse either, which is how I read your comments (perhaps inaccurately). I think whether it feels like The Expanse will mostly be down to the story they tell and the characters they feature.