What changes in Space Adventures?

[Yora]

• Star Trek and Star Wars have very little space combat.

Unless you count the Star Wars movies, I guess.

Something curious I noticed yesterday thinking about how my campaign could have planets with multiple states, is that about every sci-fi setting seems to have one big human empire or federation or something. Star Trek, Dune, and Star Wars had it, and since then it appears to have just become a default standard that I never see really questioned or anything interesting done with.
There's also so much war that the distinction of Military Sci-Fi seems almost redundant. I was thinking that with how I want to set things up at the basic level, space armies don't make much sense in the big picture, and there should be more focus on paramilitary police forces that maintain order and security inside systems rather than wage massive battles in the far corners of the galaxy.