Comments.
1, Stardock is not Paradox (size matters), and how woefully documented are the hugely complex Paradox games? It's a question of where do you want to put your dollars and work-hours. I also seriously hope the documentation gets better... the galactopedia is a great idea but it's bare bones now. First thing I tried was to look up a resource to see if I could figure out what it is used for. Wasn't a great success, LoL. Might also mention in the same vein the tutorial, which shouldn't be a puzzle but a guide. I struggled to work on it for days. It's getting better but that's not saying much.
2. I understand that galaxy set up is a trial and error thing when I would hope for a more intuitive procedure. For example, I tried to set up a many sector galaxy with roughly one faction per sector. I struggled. To some extent a little experimentation might be required, but one should get the hang a bit more quickly.
3. I have always been able to manage diplomacy pretty well with the galactic civilization series. I think it should be a bit harder to get a non aggression pact. But if I work on it I can get it most of the time.
4. Can't comment because I never sell anything per month. All upfront.
5. I have finished culture tracks in all the games I have played. Don't know what the problem is here. My current game I just finished individualism. Those individual points do add up, for me.
6. AI suiciding is a problem. It helps clean up a sector a lot faster, but really. Are all aliens suicidal? Stardock has been good with AI so I am hopeful here. It's the hardest part of a strategy game, but they have had success in the past.
7. Nazis vs. Stalin was a total war. US vs Japan was total war. And here we have aliens vs humans etc. I think it's about right.
8. Don't know about this. Every game when I go after another faction, frequently they will sneak an invasion fleet through and grab a planet. Most annoying. I admit I haven't figured out the most efficient way to approach this. The whole business about influence and invasion tactics is something they've been concerned with for a LONG time. In Gal Civ 3 there were howls because it was difficult to build an invasion fleet, arbitrarily so. I am sure there will be an evolution here, but I think even the current system is a big improvement. Doesn't mean I am in love with it, though, and I thing that they need to continue tinkering with it to find the right combination. Frankly I don't know what that is. Specifically about blockading. Well, I think that's a very interesting topic. The fact that fleets will now fire on enemies in range without player involvement is a step in the right direction, but I don't think at this stage that solves your main objection.
The thing about Stardock, good or bad, is that they are almost never done with a title. They are still adapting GC3. So its a process.