I think there are a few items that could make the game much more interesting. I like to consider new players so I think distributing rewards among the most players is best way to achieve a more vibrant economy. Here are a few other items I believe would improve the game.

-Destroying planets. Planets owned and also enemy planets.
-Siege / parlay forced negotiation for troops planets and other resources...
-Galactic order that is not FORCED but rather incentivized through a bounty system. ( Parley and possibly some other social order....)
-Hyperspeed (x2 or x4) for ships or single deployment...
-Randomness added to the battle system so that battle outcomes are not so predictable.

The question about what makes me want to invest more? Engage the community. Make give them a reason to log in each and every day. Incentivize desired behaviors. Place points of interest all over the map each week that people need to explore to to unlock a quest or something.... The game's bones are great; now give us more!!!