Hello. I am a returning player, after a 10 year break. As I see it, the battles and wars are fought basically for "prestige", who is better, which alliance is stronger. Let's spice things up a bit. I propose the developers associate some sort of win to every region. You conquered say Central Transdanubia (region random, I play on Hungary's side, that is why I used it as example). You gain xyz money and gold in the battle that is distributed among those who fought. You lost the attack? Well you have to pay the defenders war damage reparations. Of course the amounts will have to be tested and balanced so you can not bankrupt a country in one attack or get way to rich, but also the amount should not be THAT trivial
Next, each region should have defenses, 2 types
1.) Natural: Marsh, swamp, mountain range, river, etc.. each add and subtract something, again small values but it will give spice to the game
2.) Buildable: Countries should be able to fortify regions. This should be expensive to prevent someone developing and overpowered fortress can not be attacked no matter what.
3.) Open for suggestions, but come on guys, let's fight for some in game valuable stuff, not just "ha ha, I got you"