So far sins is all about fighting. I have a suggestion to add a civilian structure.

Each planet under your command can give you a mission to protect a spawned trade or civilian convoys to be escorted to some other Star base/Civilian or Military Structures (Heck could be Engineers repairing Gauss Cannons). Each convoy will be then escorted by your ships to be protected by pirate raids or Enemy ships. It is like a particular planet giving the home-world a mission and in case of failure/success, the respective planet allegiance would be affected.

And in diplomacy there could be a UNO type orbital structure hosting diplomatic envoys from all players or allied players.