Sooo I think we all agree diplomacy needs work. Personally, I'm on the more radical side in that I want something very different, and as immersive as possible. I don't think diplomatic agreements should even be a "given" if offered at the right values.
But putting that aside, the current diplomacy model is a standard 4X bread and butter system. The unique-ish part being that you earn diplomacy and shift opinions by a certain amount of points, sometimes per turn.
I'm currently playing a game where I'm number 1 militarily, I've only destroyed 1 race, + a dreadlord colony, and I'm definitely going to murder more civilizations. I'm malevolent, and I have about 26 worlds, and my nearest opponent has 16. My tech isn't the most advanced in all categories, but I have way more logistics, plenty of carriers, and strategic resource infused ships than anyone else and I've built up at least 30 transports...
And yet. They all love me. The other 13 opponents are all near the max happiness with my empire. One guy is at cordial... so I guess I'm going to murder him for his polite attitudes and insincere smiles. Note, I'm only trading with one faction.
Why?
As far as I can tell? Because I built 3 diplomatic outposts on starbases, and maybe 5 embassies.
Is this normal for other people? If so I start to understand why alliances are tech-locked, because it would be extremely easy to get a diplomacy victory with these conditions.
Perhaps we need a "gang up on the leader if he is a human player" code for the AI. No one empire right now could hope to withstand me, but two or three out of these 13 would put me on the defensive for a while.
Granted I'm playing on Normal. But these are behaviors I would expect on normal no?