What they need to do is actually very easy but for some reason its taking literally years to do. Here is the basics:
Diplomacy: Take everything from the Diplomacy mod and implement it, pay the modder what it takes and move on
Couldn't agree more. If TW can't be arsed to add actual Diplomacy features, just make the mod part of the game.
Ideally as soon as you take a fief, you should be able to form a Kingdom. But because there's no form of Diplomacy you're totally screwed if you attempt to do that.
Sadly there's really only two ways to form a Kingdom. 1) Become a vassal and when you have enough fiefs break away 2) Use your elite party to "snipe" fiefs from a Kingdom when they are pre-occupied, then peace out with gold. Rinse and repeat, form a Kingdom when you have enough fiefs. Or take Rebelling Towns.
The problem with Option 2 is that it is sadly probably the best way to conquer Calradia i.e. never form a Kingdom. Use your elite warband, take a fief, peace out, build up your garrison, accumulate more wealth, do it again til you own the map. No stupid non-nonsensical wars, no A.I. voting for multiple wars, no A.I. to lose Parties/Armies. And #1 nobody will declare war on you.
The fact TW doesn't understand that there should be basic messages (at least for Marriages and Mercenaries) shows how out of touch they are. It is extremely impractical to ride all over the map to hire a merc clan or arrange a marriage, especially once your King and you've got a party that likely consumes 1000s of denars a day. I'm surprised they implemented Companion recall...
Peace Time Mechanics: Feasts and more interactive mechanics need to be added during peace time as peace time is the most boring since their is nothing to do
Yeah there should be some form of peace time activities. Feasts should really be part of the game now due to fog of war hiding all NPC details. There should also be activities you can do in Towns/Villages to earn money/improve relations that don't involve killing people. Maybe you help farm, build a house, etc. something that could also improve the non-combat skills (Smithing, Engineering, Medicine)
Training or drilling your troops would be nice too. You don't build a professional army by fighting bandits, you build one with time and money a.k.a. training.
Population: This is probably the one that should be implemented of all, let me explain. Wars need to be meaningful and make an impact on the economy and powerbase of clans. Currently a clan with high relations with villages and towns can lose an entire army and instantly replenish its troops. This is clearly flawed. By giving a village, castle and a city a population that function on an economic level and military level (aka troops to recruit) this will make battles meaningful. This would also impact the economy of each nation, that when losing an extreme amount of peasants in a war their economy slides to a griding halt.
But if I am honest I think the Population mechanic will never be introduced even though the modding team behind the Jerusalem Mod is doing it. Some part of me believes that the dev team is amateur level at best given their previous track record, slow updates and lack of a clear roadmap.
I don't think we need population per say, technically it's implied high prosperity = high population
What needs to happen is more like this IMO:
1. Way less recruits (and no free troops for Lords) - ideally a Notable should spawn 1 Recruit a day, and
only when all slots are filled do the existing troops start to increase veterancy. So if you deplete a village, it would take about 1 week to get a full set of recruits, 2 weeks for basic tier 2 troops, 3 weeks for tier 3 troops, 4 weeks/season to get end up with tier 4 troops. Provided no one recruits from village in that time... This would make battle loses far more meaningful.
2. Battles should be somewhat slower, less frequent (i.e. more consequential),
and definitely should not be fought to the death. If your leading a war party/army and you fight to the death you've effed up badly. If your losing a battle retreating should be a viable option in most cases. This whole thing you need "Tactics" to retreat is harebrained. No, just let Parties sacrifice their wounded to escape and give a speed boost so you can live to fight another day. Also there needs to be some surrender options like spare troops, spare you, etc. Also the A.I. should surrender when totally outmatched. Even the most crazed Bushido Samurai would not fight to the death if they could help it, the A.I. should value their lives/troops.
3. Don't need looters and bandits everywhere; looters should spawn from raided villages, bandits should only spawn from hideouts.
Basically make battles have consequences from beginning to end. As is the only battles that truly matter are sieges.
Also be nice if Companions reacted to more events, still planks of wood after 4 years. Seriously why does Warband have more fleshed out companions?
It's definitely Amateur Level, FFS why are some Bandit Bosses voiced but others are not? How can you not be consistent in implementing which dialogue lines are voiced?! I believe there is a small handful of knowledgeable Devs, maybe like a dozen, and then you've either got a bunch of would-be intern "Game Developers", everyone else works like 2-4 hours a day, or most everyone is working on a new game...
I don't think there's any DLC package that TW can put together that will compare with mods. If they do make a DLC, let's be honest, it will simply be to siphon more money from those playing on consoles - who will never have mod access.