Stability is nessacary to prevent large nations from becoming to large. Its the factor that makes being a small nation better.
Too much potential for bias and/or accusation of bias.
Ok, so the casus belli system (where you had to appeal to the GM to go to war) was unbaised. The fact that the GM decides every battle with RNG can't be baised. The stories the GM writes about events isn't baised. The NPC's aren't baised. Your Infamy isn't baised (allowing some cases to have more infamy then others) But somehow, deciding public support of a country is...
Here is my suggested system.
Add another policy (like in TF's):
Nationalism vs Multiculturalism
Nationalism raises stability and decreases the negative affects of war, while Multiculturalism gives a small boost to the economy and increases relations with NPC's
I hate your Infamy because India declaring war on China (just an example) would be a more just war then America declaring war on China (due to border disputes, having hindu's outlawed etc. etc.).
I like things that add to the role playing (If you suggest NESes I will kill you) and this is a great way to add to it. having a propaganda campaign advertising to your people the reasons for war.
However there should be some Cultural Policies added to the game that just decide the People of your culture (Multiculturalism would also decrease the negative affects of these). For example:
War Mongering vs Pacifist
Racist vs Diverse
Athletic vs Scholarly
Conservative vs Liberal
Sexist vs Women Rights
Hard working vs Lazy
Religious vs Secular
Each of these would determine the average man's opinions in the country and government actions would affect stability based on the peoples views of the government. Then you add in this political policy:
Propaganda vs Public press
In Propaganda you can change one cultural policy to any value each turn. In Public Press, you can change as many cultural values as you like, but can only move each slider once per turn.
This adds complexity to the game, but not much.
The other thing to consider (which I am) is not state the positive and negative affects of each in game. Allowing the player to choose based on his roleplaying rather then based on whats best in game.