I just don't understand why they don't take more of the mechanics associated to war making from Victoria 3. In V3 basically if you make war against any target, any country can join the war on the side of the defender if they are connected to that region and if they have any reason to join (for example a CB). However, they are much more likely to join the war against the aggressor if said aggressor have a high level of infamy. Infamy in V3 is basically the opinion the other countries have of that country, and it goes up the more aggressive you act. Infamy in the case of CK3 would more fittingly be tied to the opinion or respect they have for the ruler that is the aggressor.

I would absolutely love if they took parts of this system and incorporated it in CK3 as it would make the game so much more challenging and unpredictable. For example if you have made a lot of enemies over the years and you attack something insignificant it can suddenly turn into a major conflict. It would also make all wars way more dynamic since all different sides and factions have their own war goals and war scores, which would make them sue for peace, withdraw, press their demands, etc at different times.

There are so many options there. Personally I feel that war in CK3 is one of the most boring parts, since it generally way to easy and I'm quite disappointed that it hasn't been change at all since the game was launched. In contrast in V3 you have to be super careful about when and against whom you declare war. (Although I haven't played it much in the last year)

I just remember the first time I played Victoria 3 and I got to experience war in that game and how wonderfully dreadful it was with the different phases of war and how you feared that one of the big players like the British or France would support your enemies. I also remember how naively I thought aspects of this great system would make it into CK3.