if i may add some thoughts
-
Disloyal generals and governors. In civil wars I would add some penalties that really screws the social balance so that you do care if a civil war triggers and the actual result of it (increase the revolt risk for affected pops by region or alligiance, automatic political prosecution-enprisonment-exile-assasination of losing characters that you may find useful, families vendetas, stability hits,...). Usually in EU I do not care much because it has not much political or gameplay consecuences, the country moves on very quickly and the war is never very challenging.
-
characters don't have place of birth in information. Interesting
-
cursus honorum. I would like to see cursus honorum affecting greatly what a character do and what can be elected to. no teenager generals please. Also put something on the portrait where I can see his level so that I can understand at a glance what offices can he access and making him a threat to other families if his stats are better that their members' candidates (ie. a youngster from another family with more charisma than an appointed governor member)
-
Divinations. I want to see politics in omens. populist pigs do not support other factions' politics

. I mean, if you choose a pontifex that hates the consul, or from a faction that opposes the consul's prepare to find a twisted liver in that pig. Moreover, if would be nice that pontifex office or any other is not completely chosen by the player but in some cases (you may not have the "political capital") other factions may overrule the candidate preferred by the player. This, or some other mechanic alike that if your mana points (civic?) are not enough the state will start to behave more organically.
-
limited number of families. I do not have a problem necessarily with the number of them but their possible passiveness. I would like to see them competing with the player to take control of offices, generals, governors. Also, I want to see clearly in the interface what are the families' objectives, alligiances, who they want to assasinate, what wars they want to start or to end, games or buidings they want to pay for to increase their popularity/influence... I am quite happy to see the new family interface but I think Paradox has a very good opportunity to really make the game feel like a different "animal" and not just a reboot of EU. I think this can be achieved with a dedicated interface to each family stating their ambitions, resources they have, their connections, their offices or regions of influence and your available interactions. I think that would give a better taste of what politics is about, dealing with groups that you do not fully control and have their own initiatives.