Something that saddens me is that a lot of nerfs have created their own problems. To name a few, we have:
- The pre-RoI faction wars allowed both sides to call in allies but led to some ludicruous event troops spawning and allowed foreign realms to try to take land from individual revolters. A possible solution would have been to nerf the event troops (that requires two lines of code per spawn_unit command), disallowing war declarations within a month of starting another war (which probably would have been possible to adapt from the EUIV system or could have been scripted with character modifiers), and allowing the revolters to call in one another if they get attacked. Instead we got the temporary titles that prevent the revolters from calling in foreign powers and that make it all but impossible for smaller realms to take advantage of a civil war nearby as the AI won't attack what it percieves as a numerically superior foe.
- Pre-CM, it was possible to choose between many weak vassals, which were individually weak but harder to please in general, and vassal kings that were a bit upset over being vassal kings and more of a threat but that were easier to keep track of. Instead of a nerf to general vassal opinion and opinion from piety/prestige, we got the vassal limit, which is an arbitrary number that makes it as bad to have a count as the one vassal over the limit as it is to have a king over the limit, and the chance for vassals to break free with zero consequences if you happen to end up above this number and die. It also encouranges setting up the realm so that you can raise a large number of levies in the same province even though it makes no sense for all the levies from Britannia to appear in Sinai because the king of those kingdoms have a random county in Sinai.
- Pre-Conclave alliances were possible to avoid for a small prestige hit and the loss of some opinion, while not being 100 % certain. The prestige hit could have been scaled somehow (e.g. loss of 2 years of monthly prestige instead of a flat -25 prestige), and all allies could have gained a stacking negative opinion modifier vs. the ruler refusing a call to arms (unless that ruler was involved in another war or had a good excuse (such as being allied to both sides or the war being fought over their de jure land or titles they also have claims on)), but instead we got allies that always come to help you even if they are unneeded, have their own problems, or have interests contrary to aiding their ally in that war.
- Blobbing has always been relatively easy if you know what you are doing. It could have been made more difficult by lowering the efficiency of having a large realm somehow (lowering income/levies from non-demesne provinces to e.g. (0.5 +0.5*exp(-kx)*100/y)*[tax from a specific vassal] (x being number of vassals and y being distance between capitals, k a non-negative constant <1) would make large realms with many vassals gain less from distant expansion than a small realm with few vassals expanding closer to home), adding a cooldown between declaring offensive wars, and making it possible to offer to join (defensive) wars just like you can join holy wars, but instead we got coalitions (or pacts, as they now are called), which many feel are unrealistic (in various ways; some don't feel they are suitable for the era, some don't like cross-religion alliances, and some don't like that they don't really take into account where you have been expanding as much as they take into account how much land you have gained). They are still being tweaked, but it currently feels like they mainly slow down blobs (which probably makes the more stable) and bring with them new balance issues (something I feel was made clear when there was a dev reply suggesting that the proper way to fight them was to use favours (which are DLC-exclusive) and gamey tactics (conquering land and releasing it to burn infamy)).
CK2 used to allow for varying degrees of roleplaying and blobbing based on the player's preferences, but it feels like arbitrary limits have been added to stop a percieved problem (blobbing) and the roleplaying additions haven't made up for this and have been extremely unbalanced in several instances (e.g. seduction).
A lot of the stuff that has been removed o changed could have been kept the way it was and left it up to the player to decide if/when they wanted to use it (with those playing multiplayer games agreeing beforehand that e.g. the assassination button was off limits). Sure, the devs might find some mechanics exploitable when it comes to achievements (even though the initial Ironman version allowed you to get a lot of achievements with these mechanics), but it is annoying to see that more or less working mechanics are replaced with mechanics that don't work better in all respects.
Tl; dr: There have been a lot of changes that haven't always been an improvement, and a lot of exploitable mechanics were up to the player to use (or not) and could have been fixed less arbitrarily.
