More abstract things on top of abstract things? No. Just no.
It's hardly abstracting on top of abstracting. The differentiation is there for a reason and actually adds to gameplay. Ignoring the huge post that came after it as if I did not explain why the system has huge practical benefits in-game that are not very hard to understand, but can radically rebalance the game for the better isn't a very good argument.
Not to mention that cores are hardly "abstract" unless you think that administration and bureaucracies are somehow abstract.
Likewise, the difference in the administrative lands of your kingdom/empire that are considered a core part of your empire (De Jure cores) and are home to your people (e.g. the people who are seen as "full citizens" and are properly represented, as with the British in the UK as opposed to the Irish in the UK), as opposed to those administrative lands that aren't (De Facto cores) and contain your second class citizens (see the previous example), is hardly an arbitrary abstraction, but actually rooted in reality and how countries actually functions.
Because of this, you can't have war to further some other objective. The reason you go to war is to get stronger so that you can win more wars. War is the fundamental gameplay, and your actions are ultimately in support of war.
In order for there to be some motivation to play tall, or avoid blobbing, or whatever, you have to have some actual compelling gameplay that isn't war. Then you could go to war in support of that other mode of gameplay. If trade management were an actual game, rather than just placing a merchant, you might want to go to war to further your position in the trade game. As it is, you might go to war to expand your trade, but it's ultimately so that your trade will enable you to win more wars in the future.
The two are not mutually exclusive. The game can encourage building tall while still keeping a focus on war - although expanding peace time features would still be nice if only to differentiate gameplay some. If periodic periods of peace gave you an advantage and made you stronger instead of encouraging constant war and making any time you aren't at war a waste of time, then the game would benefit. It doesn't have to be perpetual peace, but if you had some reason to slow down the pace of war for reasons other than "let manpower slowly tick up", but could also manage to put yourself in a better geopolitical position for a future war, then the game benefits. Likewise, if you rebalanced the game so that war could be about more than just blobbing and allowing other options that can be, under certain circumstances, preferential to just blobbing, the game would also benefit.
Last edited: