Wish I could put my finger on exactly what GC3 screwed up. I mean, besides the obvious dumbness with Steam Workshop mods. I think it's how linear it felt. Sure, you *could* devote all your research to production or government techs, or have your shipyards cranking out builders to create dozens of starbases. But then the AI, even "good guy" ones, would come kick over your sandcastles and pee in your cereal thanks to the huge "you are weak" malus. If you didn't focus on military power, even on lower difficulties, you would inevitably be sucked into wars with everyone in the galaxy. Plus, the size of a large or bigger galaxy combined with the slooooooow speeds of your ships was just... so... boring.
And back to the mods, I HATE having to play a full game as a downloaded Dalek of Galactic Empire civ just so the AI knows to use the custom ship mods for them. And even then, just the ones I specifically use. Otherwise, instead of shrieking monotone omnicidal cyborg maniacs, you just have generic fleets only differentiated from other factions by the leader portrait.
Grr.