CDR Salamander did a bit on this a few days ago and as a sci-fi fan I think he hit it: spaceships have a direct lineage to navies and as such should follow nautical traditions. Spaceships have captains like Kirk and Piett. Troops with guns that serve on these ships are Space Marines.
But do they have that same lineage? I mean, we haven't had any real "spaceships" in the sci fi sense you're talking about yet. Airships also have similarities to surface ships in how they operate, yet even the biggest heavier than air platform is not run like a ship. The article that CDR Salamader links to doesn't seem to grasp that there are aircraft with large crews, that air traffic control is a thing, and so on (also I find it hilarious that he brings up warhammer 40k's space combat, which is pretty much age-of-sail combat in in space, right down to broadsides, crossing the T, and even ramming).
I'm not saying that it won't work out that way, I just have to wonder how much of this is us applying what we've done in the past to a thing that doesn't exist yet. And if unmanned aircraft are cheaper than manned aircraft, I expect the same is true of spacecraft as well. I envision this force being a lot of guys sitting in command centers pushing satellites around. I don't really know if it is a good idea, as it would be a military force without a real unrestricted line / combat arms officer corps...at least as long as we have treaties against weaponizing space. Also, I think that without a warfighting mission of some sorts it would eventually become the most clogged up, GMT heavy, bureaucratic service in existence as there would be no one around to say "we ain't got time for this crap."
Also...anyone else think this totally came out of the blue (pun intended) and that the cyber guys would get their own service first?