Remember how easy it was to score money and resources off a faction by declaring war on another faction they were at war with at the diplomacy screen?
You'd get what money and resources you wanted, and then you'd sit around doing pretty much nothing to actually earn anything.
That's why players need quotas set by factions on how many opposing ships that require destruction.. to earn those pretty credits.
GalCiv would be much more competitive and exciting this way.
Then again, I haven't played GC3 so maybe I'm wrong. I know nothing of the game play and balancing issues.