Not to mention the 3 core members are not Democracy either. U'lduar is a monarchy, Galandia is basically a pagan theocracy, while Limsa is ... technically a dictatorship with the leadership elected through a might make right process.
I'm not sure what you're talking about here, since most of the thing you said here doesn't match with what in the game or would make the leadership super stupid. For the most part, every nations we came across were under crisis and had to beg for outside help, it makes no sense what's so ever for them to go back. Not to mention, prior to the conclusion to the 6.0 story the Garlean Empire is a threat. Going solo right after gaining independent seem to be a terrible idea.
- Isghard: they just lost the head of government, with the whole doctrine turned out to be a 1000 years lie. Without fresh respective coming in, the millenia distrust between the classes would come to full blow, and this time there is no longer an external enemy with an existential threat to keep them from killing each others ... not to mention the left over heratic population. An isolated Isghard would go up in flame in a civil war.
- Ala Mihgo: considered Albert triggered the war to drag the alliance in, and thus have them liberated. Even if they kicked the Alliance out and become an isolanist again, they would have a broken country with no resource to rebuild, and still gonna be on the front line against Garmelean.
- Doma: going solo mean they'll be by themselves holding the Eastern against the 12th legion, a battle they already fought and lost. At the very least, Doma would still have to unite with Dalmascans and Borza. At that point combining the Eastern Alliance with the Eorza Alliance make no different from an isolation pov.
You seem to want variety simply for the shake of variety at the cost of logic. The geo-political situation in Eozea make perfect sense. The new leaders may be portrayed as idealists, but it doesn't change the fact their action is exactly the same what the most pragmatic leaders would do assuming said leaders are not stupid.