Two thoughts which i hope would be have a good payoff-to-investment ratio:
1) Featured mod-wise, can a (ressurected) civ-defense or king of the hill ("hold while we find this key intel/character hidden in the area") game be included now and then? Increases narrative feel hugely and allows for variation in game types. I would expect this would not be the first thing done but would be -relatively- painless to implement.
2) could we consider including some AI players in factions (AIx, probably no omni for allying purposes) to act as 'basic grunt' characters. Maybe even 'undefended' worlds get an AI defender so at least the attacker gets a (rather easy) game to make up for their waiting if no defender shows. Benefits: makes battles and the universe feel bigger, makes all players feel like heroes and great players feared across the galaxy, allows (if desired) factions to randomly attack or defend during less populated server hours. Bonus: players who feel like they can always at least get a game (that has some narrative effect) will be more likely to log in and play at these times, and will therefore encounter one another! I'm guessing a random probability of entering an AIx into a game on either side would be pretty easy to code? . More advanced features (eg faction 'generals' prioritising which worlds get AI support) could be left to later and added in a bit at a time.