We already see with a galactic eye an empty cosmos, pulsating stars, and a near-endless supply of rocks in space with every imaginable combination of elements, and a few unimaginable ones, no doubt. Imagine the ability to make the Kessel Run in 14 Parsecs, to step into an abandoned hunk of junk and boost it in a matter of minutes to get from the junkyard desert of Jakku to the iridescent green of Takodana. In this place and time, space combat makes no sense.
Why send a squadron of X-Wings to hit one part of one world when a squadron of automated bombs can pound into it at lightspeed? Why not just shoot large chunks of matter at lightspeed to crash into things? There is enough lightspeed capable junk lying about the place, after all. There are advanced AI units and various elaborate computers. What is so different between automated attack droids, which are archaic in that universe, and automated suicide hyperspeed bombs?
Imagine, again, the power to just fly away. Why stay and fight anyone, at all? Fly on to the next galaxy, the next green world. Just fly on and build colonies where there can be a new way of life. What purpose such efforts to contain and control into an empire? What does power gain in such an economy except more power? To what end? There was an episode derided for the dullness of a trade dispute, but it was the only motivation for war that made any sense, at all, on the scale of a galaxy. The planet is locked down, locked away. Of course, what matter that? There were plenty of farms, plenty of fields, and oceans deep and country wide. Let them blockade all the universe away, and remain on the ground a people of peace and plenty. How would anyone even know they were blockaded outside of the major metropolises? Much easier and safer to stay on the surface of the world, working and living and looking up at the stars as if a flat screen. Few would be bothered by the loss of the depths in sky, just as few in England will even know what has been lost, since it can’t be measured on an individual scale.
There will just be that sense of loss, like an empty obverse of nostalgia, a future-nostalgic-feeling for what could have been.
Let them control. Why not? What could they do with it? Build an army of clones? A single line of custom virus would wipe it out. Build an army of robots? Again, a single line of custom virus would wipe it out. Would they conquer the sky? Drones are cheap and easy to build in such a universe, and kamikazi machines would require no great army to weaponize at the scale to destroy all ships. What need for sabres of light when hyperspeed stones smash through the walls and shields? Why build a single death star to destroy a world, or a star-killer base, when a seres of large stones pushed down hard enough would do the job, as well. Anyone with a junkyard at their disposal has the technology to do the same. A single CrispR machine, a single microbiotic technician, can end the war. A single hacker can pop open every airlock in a gesture. Armies are only as good as their weakest entrypoint, inside their giant metal shells. Space, itself, and biology are more dangerous than any laser beam.
And, all the things that make for war – resource scarcity, ideological purification, etc. – do not exist on the scale of a galaxy. Just fly away from anyone who disagrees to a new green world. Any hunk of junk can get you there, apparently.
War in space just doesn’t make sense. Imagining combat on that scale has never been done well on screen.