I thought about something similar to that with I guess an Ethics system. I dunno yet if it can be done, but I added and Icon (on the Politics page) with your countries ethical alignment. Basically you would answer a series of questions about your nation and you answers would equal out your ethics which in turn gives you certain bonuses or even penalties.
I would like to see something similar to what you mentioned kind of like each player's nation ruler has a certain personality which yields different bonuses.
This all comes down to Simon though as he's the one that has the code the thing!
About the Alliances... I believe they are meant just for teamwork with benefits. If a nation want to stay solo, they can. If Alliance members don't want to help out in conflict, that's the alliance's problems and maybe the members need to talk about that themselves. Just like the real world, no one has to come to the aid of another nation, they do it usually for selfish reasons, and even more rarely, out of good will.