Insalubrity:
The IGC was designed to add more historical accuracy to the game, but it doesn't really add any more of the non-combat stuff to the game than the original game did: you'll have more historical leaders and monarchs, and somewhat more accurate starting positions and relations and events. Dealing with them might give you some idea of what the real monarchs had to put up with! Playing as Brandenburg (minor power) in the IGC, if you last long enough, should give you enough good military leaders to romp and stomp in a purely militaristic fashion.
Another option is to play one of the non-Grand Campaign scenarios provided. Several of them are centered on major wars of the period, so you more or less start with a military situation and problems to solve: it's not the best play, but you can ignore or de-emphasize the non-military stuff more than you can in the longer GC or IGC(Improved Grand Campaign).
Gotta remember though, this game is set in the era of Limited Wars, Age of Reason, etc. The states simply couldn't mobilize their own resources well enough to completely smash and absorb neighboring states easily. Even if you, playing the king, wanted to do that, the people, soldiers, and other statesmen simply don't think that way: you have to operate within the envelop of what is posible in that time and place. That's what makes it a historically-based Strategy Game as opposed to a Fantasy game.
I don't mean to sound patronizing, but too many people think that Once the Game Starts I Can Change History Any Way I Want To, an that just ain't so. Even the most absolute leaders in history had to work within the boundries of what had already happened and the mindset that was in the people they were trying to lead: Louis XIV in France, Hitler in Germany, Stalin in Soviet Russia - none of them was as Absolute a dictator as the average gamer would like to be.
Personally, I think it makes for a much more interesting challange to have the historical problems to solve. One of the great advantages of history is that it can give you problems and situations that no author would have the imagination to put in a fantasy scenario!