Personally I find there to be a lot of fun in fielding a strong military and making use of it. Is fielding a strong military somehow not part of building an empire?
It should also come at a steep cost as well.
I'm fine with making walls weaker, as long as they double the current upkeep cost of military units in exchange, for example.
As of know, declaring war is too easy with very little risk of not getting anything out of it (thanks to pillaging and the aggressor getting to position his units to pillage all the important things on the very first turn). The diplomatic consequences of doing so is laughable (diplomacy in this game is non-existent thanks to grievances not doing anything!). Whereas in reality declaring a war is a very weighty decision which needs careful planning, and the defender often requires a far less impressive military force than the attacker.
Walls reduce damage from non-siege units by half or so, rather than by the 90% of something that it feels like. All capitals now start with ancient walls.
Walls now increase a stationed ranged unit's attack by 10, 15, and 20 (30 for Tsikhe) and attack range by 1 rather than having an innate ranged attack as well as give them unobstructed line of fire. Cities now gain combat strength bonuses if a melee unit is anywhere adjacent to the city center (rather than having to be stationed directly in it).
Units inside and adjacent to city centers now only take reduced damage rather than being completely invulnerable in a city (however, they will still regenerate every turn despite attacking). A player must reduce both the city's HP and the unit directly stationed inside the city center to zero before the city can be taken (if the city's HP reaches zero, the units inside now take full damage). It makes no sense that a full HP GDR newly produced inside a city with red HP will die in one hit once the city goes down.
Grievances tripled for the declarer of the war for the same action as the defender (that is, if the defender takes a city of the aggressor, the grievances are far less) Such that the moment you declare war, you give your new enemy free license to do whatever he wants should the war turn in his favor.
Declaring a surprise war without casus belli now inflicts a huge amount of grievance (300 or so). Pillaging inflicts grievances for each instance (10 per instance).
Grievances against a player reduce all his units' combat strength against you by 1 per 50 points of grievances.
Double cost for all military unit maintenance (such that you are almost required to run the -1/-2 cost per unit cards if you are going for domination).
Tiles belonging to a city cannot be pillaged unless the walls are down.
War weariness now afflicts only the declarer of the war. When war weariness reaches a certain threshold limit, the attacker is forced to automatically peace out with a white peace (players can decide to make peace before then with a deal)