The diplomacy system would have to be overhauled, right now I don't play with it at all as a result of the sheer volume of nonsenslical, strategy-breaking AI demands. Demands need to be context sensitive based on the current situation, so that you don't have allies who demand you open up another front in a war you're both losing or the like.
This makes sense, though even with GalCiv 2, it seemed to me that AI "diplomacy" involved merely tributes/extortions based on relative military strength and threat of war. I do miss being able to bribe AI with technology, which leads me to the next point.
Absent a diplo system, the game is at best 3X. - The AI needs to be markedly improved. Part of the reason I think I don't see all this depth Brad is talking about is that the AI never gives me a reason to do anything but build ships.
I see a different angle to this problem -- the need to build ships would be somewhat mitigated if the effects of research were more obvious in tactical battles as they were in GalCiv 2. It just seems that even with a deliberate choice to focus on research as much as possible, the technology advantage in mid- to late-game is non-obvious, and that's assuming the researching faction survives the initial rush in the first place. In other words, it's much harder for researchers to survive the rush than for rushers to catch up on research. This might be more realistic (e.g., Germany's last batch of jet-powered fighters were overrun by a greater number of U.S. propeller fighters), but I think long time players of 4X have come to expect sacrifices made with choosing a research path yielding nothing less than 1 or 2 technical marvels/pride of the galaxy type ships being able to wipe out an entire fleet on its own, as was the case in GalCiv 2 (how I miss being able to concur the galaxy with just 3 ships). That path is less obvious in SoaSE. It is a bit annoying/deflating to have my fleet of 5 mixed types maxed-out cap ships jump into the pirate colony and have their asses handed to them by 80 - 120 presumably early tech pirate ships.
In short, I think the typical quantity vs. quality dilemma long present in 4X games is largely absent in SoaSE. This is a game more about counters.
As it stands, I build a few things around a planet, upgrade its infrastructure, and never look at it again. - More needs to be done to make one game different from another.
What would be the purpose of this other than to produce awesome ships?
There are so few options in building your empire, and its so easy to pursue all the techs in a long game, that each game seems the same as the last. This is the biggest problem with the game, IMO, and the thing that most distinguishes it from "real" 4X games I've played. Branches in tech trees, better differentiation of the races, the aforementioned greater pool of empire building options, any of this would help.
Besides badder ships, what other purpose do those features serve? Not that I disagree, but perhaps I just lack imagination.