I already disliked all the references to US history in Fallout 4. To me, cowboys feel misplaced in a science fiction universe. It’s just personal preference though. But the question stands: are large parts of the main story related to the cowboy characters, or does it work mostly without?
To be fair - there is a tiny bit of space cowboy-ism in The Expanse, tough. But it is very tongue-in-cheek, even in-universe.