Well at least you agree with half of it then :P I kid. Certainly much of it is controversial, but I have seen many people complaining about these issues, so I don't think I'm the only one suggesting that certain tactics should be less effective. I'm mostly targeting grossly effective tactics which themselves limit gameplay options because why wouldn't you choose the most effective tactics? Many people agree that resists, charm, summons, combat stealth, leadership, and cc are pretty ridiculous, so nerfing those would make other skills more appealing, the game more challenging, and actually increase options. Sure, you could make arbitrary rules to yourself to not use certain abilities or tactics, but then you're just limiting gameplay options once again. If all options are viable, than the game is more fun.

I realize that blanket changes to CC would affect players and enemies alike, but I found that I used CC far more often than enemies used CC on me, so general nerfs would overall have a net benefit to the enemy in my opinion.

I think I'm mostly offering mechanical changes, not simple number tweaks. A few number tweaks yes, but that's to be expected in a discussion of balance. Haven't tried it myself, but Rhidian's mod sounds like a good start to that, but not dealing with a lot of the problems I have in quite the way I'd like. Starting the game with -100 resist is an okay solution to resists, but I imagine that must make the first half of the game much harder, which is fairly well balanced as it is. I think making gear and rubies give less resist would be a better way to make late game harder but have less of an effect on the first half. Also I meant to add that they should make summons have more interesting spells, but forgot.

I agree that AI is the big problem, but numbers and mechanics need work too. I think there's two ideas of AI going on in this thread: predictive AI and responsive AI. An AI that predicts what the player could and likely would do, takes into account his or her actions and updates these predictions to make the best possible move certainly takes much more computing and coding power than an AI that has fairly standard behaviors but reacts to player actions in specific ways. An AI that always freezes a charmed ally is much easier to implement than an AI that decides if that ally should be frozen or if it would be better to just attack the player or do something else instead.

Finally, totally agree that Larian should make much more of the code available to modders. I'd try making some changes myself, but I'm waiting to see what Larian does before I dive in myself.