I think there are multiple issues with current implementation contributing toward the overall "experience."
The "kingdom AI" has no real goals in its warfare. It'll try to take over as much as possible, but it's done in a "throw current factional strength at it and ignore everything else" way. Factions/Kingdoms SHOULD require some kind of "war goal" on a more detailed level than "eradicate them before they eradicate us."
TW could easily pilfer basic implementation guidelines from Paradox titles. Start with tagging settlements with "core faction" for each of them. Then, whenever the war declaration code runs, check if any "factional core" settlement is in enemy hands - if so, give it a much greater weight than just declaring a war on some faction half a map away because their current strength is lower. Consider border continuity before going off for some distant target that won't be successfully defended anyway (and if will be defended, it is at the expense of factional territory elsewhere). Most importantly, make war declarations based on overall factional lords' current priorities and, to a lesser degree, personality traits. If half the kingdom consists of lords running around getting fresh recruits, with half the villages raided and pillaged, the king should have serious problems getting the support (both political and in practical terms) needed to declare a war on somebody. When a lord can reply with "I ain't got no troops!" to war summons, and it's a genuine grievance, why declare a war in the first place?
The focus should be twofold - maintaining factional "core" territory in own hands (and preferably in unpillaged state), and expansion as a secondary goal. I'd also add to this that most factional leaders SHOULD concern themselves with prosperity of the lands they rule over, and keep in mind the need to allow them to recover, with limited if any warfare, from prolonged conflicts. They'll get war declared on them by others, less affected, frequently enough anyway.
And the whole goal of a war declaration should be something specific. Mostly something along the line of "we need to take this town," or "we need to retake OUR castle that those bastards stole from us." Then you can add lord-to-lord relationship and personality traits to it. So that capaign to expand the faction to a new town might be faster joined by honorable lords, whereas greedy ones who see no chance in the ownership falling into their hands do some raiding instead. So that a clan with poor relatioship with the previous owner of that castle the liege is mobilizing to retake (something the game would need to track) is that less likely to contribute to the army doing the retaking. On top of any trait-driven inherent predisposition or dislike for warfare in general.
Then the internal conflicts between the lords actually start to matter (and not just in a player-AI setup), and personality traits come to life.
We don't have even basic lord-to-lord relationship implementation yet, so hopefully it's something that's coming, but individual lords should also react (in a "+/- relationship with liege" way) to demands that go against their personal priorities. Somebody trying to raise an army and rebuild their devastated villages should not look kindly on Ravangad-type "leader" declaring meaningless wars left and right, though they might contribute toward strictly defensive actions. Lords participation in "armies" should be driven by this kind of "personal" priorities, so that while they may help maintain soverency of their factional territory, a faction with multiple lords still recovering from past conflicts should have limited, if any, offensive capability operating outside of their territory - something the ruler, and factional counsel, should be able to determine BEFORE making a war declaration.
Might help if there's more granularity to diplomacy than just "war" and "peace." Just because there's a truce it doesn't mean that lords can't raid (hopefully DISTANT) villages of the opposing faction, or participate in small-scale skirmishers with their peers from the "other" side. It's certainly far more "historical" than current "whoops, here's the truce, stop fighting lads" situation we have, and would also mean plenty of opportunities for non-bandit engagements for player even during the luls in open warfare.
As an example, we could have four "diplomatic" states: Peace, Truce, Tension, War (feel free to label them more appropriately, more focused on writing down the ideas bouncing in my head right now than to find the right labels
).
Peace is what it is - everybody behaves, nobody attacks anyone, and, aside from starting few days, probably something rather rare for factions sharing borders.
Truce would be a period of "official" non-combat - neither caravans nor villagers get attacked, but lords may still butt heads in open engagements because of what Sir Wrong Side said about our Liege (at least that's my official story and I'm sticking with it!). Basically no territory flips or raiding, but very much lord-on-lord combat for parties not doing anything much at the time they meet. Truce should have strict time limits, and should occur, rather than Peace outright, if there are any remaining grievances (they have OUR castle/town!), or as a direct selection in terms of diplomacy calculations (in two weeks their other enemy should bleed them enough so we can take what's ours, by Neretzes!). In case of no persistent hostilities, should slowly degrade into peace (and be formalized as such when the "aggression" counter goes low enough, or other conditions make it preferable earlier).
Tensions would be a period of "unofficial" warfare - caravans get attacked, villagers harrassed, villages raided, but no settlement ownership change. Might even see armies gathering to curb down the aggression of the enemy obviously on the wrong side of Justice of the conflict, and large scale battles as an expression of weaponized shows of dominance. Pretty much an escalation from "Truce" with enough fighting between lords of each side. There also SHOULD be a way for a factional ruler to attempt to keep this escalation from happening - either making grievance payments ("your lord attacked out lord, gib one million dolla- ducats!"), some temporary policies in effect ("attack those sods, lose your fief, or at least have to cover the expenses of diplomacy that follows"), or, dare I say, starting up feasts and tourneys to keep the troublemakers occupied (make the butter flow!)
Finally War itself - a righteous conflict indubtibly sanctioned by the Heavens (or applicable religious concept) themselves to rid the world of those filthy *insert faction name here*. Or simply to take back something that is rightfully ours, historical evidence possibly notwithstanding. You know how it goes - everybody has a bad time aside from the scavengers and the player*, as it should be, and it's something officially declared by the faction leader (preferably with approval of their council).
*Player having good time not guaranteed.
Um. I probably should stop at this point. Hopefully it's resonably clear enough what I'm trying to present.
Adding population mechanics making recruitment more in line with state of factional settlements, rather than be something mostly indifferent to it, could work much better with all of that in place, precisely because it wouldn't just affect the outcome of conflicts, but also dictate their frequency as part of the war declaration calculations.
P.S. sorry for my English. It's not my native language and sometimes when I type fast I make mistakes. I'm multitasking right now, so it's what it is.
Better than a native's, at least in the judgement of somebody with painful exposure to the results of the American public school system...
