Almost everything you suggested could be done with the current mod tools if anyone wanted to go to the trouble of writing the events, traits, ambitions, and decisions for it.
Possible? Absolutely. Easy? No. Low-overhead? No. I'll point you towards, for example, the warrior skill trait group in The Prince and the Thane (I'm not sure if that mod was the first to use it; it's just the first mod I played and saw it in). You can be a lousy warrior, trained, skilled, or masterful; events can cause you to gain or lose a level of warrior skill. Under the hood, it's run like this: there isn't one "gain warrior skill" event. Instead, there's one for each potential level you could be at. They all have the same text, but different effects - e.g., a Trained Warrior who gets a gain-skill event will lose Trained and gain Skilled. It's a pretty simple and straightforward system for having a tier-based trait group, and there's nothing stopping anyone from expanding from there. If you wanted, you could write a whole series of traits and events giving tiers to Just/Arbitrary, Cruel/Kind, Content/Ambitious, and so forth. You'd have to rewrite just about all the current events in the game - and copy them several times over - so the overhead on the game engine would balloon dramatically and it would probably be unplayable on a slow computer. It'd also be an extremely large undertaking in terms of man-hours. But it could be done.
This is a change that is extremely easy to do with the game as it stands now. It's just a matter of adding the extra levels of buildings to the files.
Starting to get tricky to do. "Fear" isn't an element of the game, and any attempt to simulate it would be a clumsy hack at best (e.g., you could add a "Frightening" trait that gives an opinion bonus with vassals, and make most tyranny-granting actions also give that trait). Plots to free prisoners can already be added - I think a few mods have them. Tying success rate in to dungeon quality would be moderately tricky, because you'd have to decide on which dungeon improvement to use - Patricians are the only ones who really have a "capital" holding, rather than just a capital county. But there's nothing in the game preventing you from using the capital holding of the capital county; the triggers are all there. Similarly with more torture options.
Possible? Absolutely. Easy? No. Low-overhead? No. I'll point you towards, for example, the warrior skill trait group in The Prince and the Thane (I'm not sure if that mod was the first to use it; it's just the first mod I played and saw it in). You can be a lousy warrior, trained, skilled, or masterful; events can cause you to gain or lose a level of warrior skill. Under the hood, it's run like this: there isn't one "gain warrior skill" event. Instead, there's one for each potential level you could be at. They all have the same text, but different effects - e.g., a Trained Warrior who gets a gain-skill event will lose Trained and gain Skilled. It's a pretty simple and straightforward system for having a tier-based trait group, and there's nothing stopping anyone from expanding from there. If you wanted, you could write a whole series of traits and events giving tiers to Just/Arbitrary, Cruel/Kind, Content/Ambitious, and so forth. You'd have to rewrite just about all the current events in the game - and copy them several times over - so the overhead on the game engine would balloon dramatically and it would probably be unplayable on a slow computer. It'd also be an extremely large undertaking in terms of man-hours. But it could be done.
This is a change that is extremely easy to do with the game as it stands now. It's just a matter of adding the extra levels of buildings to the files.
Starting to get tricky to do. "Fear" isn't an element of the game, and any attempt to simulate it would be a clumsy hack at best (e.g., you could add a "Frightening" trait that gives an opinion bonus with vassals, and make most tyranny-granting actions also give that trait). Plots to free prisoners can already be added - I think a few mods have them. Tying success rate in to dungeon quality would be moderately tricky, because you'd have to decide on which dungeon improvement to use - Patricians are the only ones who really have a "capital" holding, rather than just a capital county. But there's nothing in the game preventing you from using the capital holding of the capital county; the triggers are all there. Similarly with more torture options.
Disagree with the first, agree with the second. It's actually got a very impressive scope; it's just that real life has an even more impressive scope.
Impacting AI willingness to marry based on wealth... first truly impossible suggestion for modders I think. I can't even think of a way of hacking it. Diplomacy as a two-way trade instead of one-sided deals is another thing that (I believe) can't really be done in the game now - but you could certainly add a decision to Offer Bribe for <Council position>, which would cause the liege to either accept the bribe and you get the position, or decline the bribe and you don't get the position.
