I wish when you dencounced or DOW'd, it would offer you a popup box of "reasons" you could click. Then each other AI could "react" to the reason with a diplomacy bonus or penalty depending on the reasons.
This would allow the AI to treat each other the same way, and have games based on consequences and reasons. "We also despise heathen religions in our lands" - "You have acted against our faith". or "We like that you declared war (because) of City State Bullying." - "We despise people who interfere with our behavior toward City States." - "We like people who declare war to protect (Polynesia) our weak friend." - "We don't like people who declare war because of espionage actions."
This would add a whole new dimension to diplomacy where reasons matter to some extent.