I agree with you. But that is not a problem with the SoD, but rather with military focus in this game altogether.
Maybe what leads to war so often in this game is the underlying simplistic system that still, more cities automatically mean more research, more culture, more influence, more parallel production and (when caring a little about timing and placement) usually more money. Sure, city-spam has been penalized in CivIV compared to CivIII, but the system still works that way. And the question now is not only 'How do I get as many cities as possible?' but more like 'How do I get as many cities as possible which I can still support?'.
Another thing might be that the AI is either not focusing enough on its 'home economy' or that there just isn't enough economic depth to deal with in the first place. That leads to the question 'Every thing is in order at home, what do I do now ?' and nations tend to go for conquest in this game.
But all that is leading away from the question of this thread