EQ, I will admit that I have not participated in many NESes, nor do I think I will ever be terribly active in this community (which is why I like choosing smaller, fringe nations).
I do think though, that what you have said about your approach to NPCs makes sense. While logical behavior is nice to see in the system, as spryllino suggests, I feel that by using RNGs, you're taking a bit more realistic approach to things. Yes, there are always choices for nations to make that are more logical than others, but I think we to remember that this chance shows us the little events we don't don't think about. While we'd like to treat our governments as unified machines, they aren't.
Perhaps the Minister of Defense wake up with an stomachache the day he is supposed to receive a vital military report and give his opinion on the matter to the PM/Kaiser/Czar/Mugwump. And lets say that the messenger who has the report wakes up late, has his horse go lame, and is assaulted by a wandering band of gypsies and then is left for dead. Without this vital bit of information, and feeling a bit more grave than gravy, he rambles aimlessly about military anecdotes and a good joke about merchants and thieves he heard last night. Now the ruler not only has a poor opinion about his Minister, but not a clue about what to do. And why should he? That's why he hired the bloody fool in the first place. Lets just move some men and boats and put on a good show and nobody will notice. Next thing you know, the economy is in shambles and you're living in a post-apocalyptic Fascist democracy with radioactive cockroaches banging at the gates.
Of course this scenario will never happen. But by using the RGNs and assigning probabilities to set of events ranging from likely to feasible, to "who knew?", you're leaving the door open for human error. Sure, you're going to behave logically most of the time, but every now and then, somewhere, and somehow, something happens that prevents everything from happening logically. To not include that possibility could be construed as "railroading." While I wouldn't go that far, since you can still have a great experience and variety of outcomes without the RGNs, I think using RGNs has greater potential for development overall.