It's not a matter of civility, it's just a quality they've acquired. Besides, I'm thinking more of Data and how silly he comes off saying shit, because it is so self consciously edgy.
That being said, I think there is cursing in Star Trek Beyond, and it barely registered. It was done in a far more natural manner, not for shock value.
I'm not keen on the quality of language thing. If its acceptable in period drama's, surely it's fine in the future.
But yeah, the Data stuff was really awkward. To me it's down to presentation as it's the geek trying to be cool stereotype-ish thing and came off kind of like being 13 and swearing in class more than a natural thing that fit in context.
Beyond and Generations had the same logic in one swearing scene, in terms or writing, but it came off a lot more naturally as it wasn't done with an immature snicker. Just.... done.
I can see it being used far more fluidly in Discovery. And as a contrast.... I find it annoyingly strange no one does it in things like Arrow. Understandable, but the niceties are really jarring considering the enviroment.