On one had that is realistic.....
Look at North Korea... asking for aid even though they are loosing the war (If you didn't know, we never signed a peace treaty with North Korea, and are still technicaly at war).
On the other hand... not every country is the same as North Korea.
If you added more variables to the diplomacy.... like have the AI leaders with the Irrational flaw make irrational decisions.... The arrogant leader could demand 60000 gildars even when your kicking his but. Make other traits/flaws have diplomatic impact on the game.... you can randomize the diplomatic aspect of your game. Right now it feels like every leader behaves exactly the same way diplomatically.