I really wasn't sure about opening this thread for many reasons.
Your courage is laudable. For that alone, I shan't destroy you.
Now, what are rules? Rules can mean many things, but the easiest way to see a game rules is to see them as the laws that makes the world work, not differently from our laws of physics. [...]
But if we accept that a rule is not only a law of physics, but it can also be designed with the intention of changing the way we play the game, what else can we do? What if we want to create a rule that helps us telling a story rather than govering a world? [...]
We can go further, the master is not an arbiter anymore, is a storyteller. [...]
What does this all have to do with D&D and BG3? [...] it's just going into a different direction, taking away some rules that don't help the narration[...]. It's not about balance or coherence, but just the emotions you can create in said moments. And this is not bad, but just different.[...]
I thinks that Larian is doing this, creating rules that lead the players into playing, removing rules that don't help nor the story nor the engagement, or working out things verticalized on the kind of story they want to tell.
All in all, an intersting take on ruleset design. If the point you're trying to make is about BG3, however, you should've included at least some examples thereof. (As you can see, I'm not too worried about seeming pedantinc ^^).
Your point still being valid (provided I've summarized it correctly), it's worth measuring BG3's rules by what they provide to its story.
The biggest change I can think of is rest management. This is an area where the DM in a tabletop game would set the cadence of encounters to heighten or release tension. The deft touch required to do this in real time is hard to emulate in a video game. Some games choose to impose strict restrictions on sleep to keep that tension. (To avoid the obvious comparison, in Disco Elysium, finding a place to sleep feels like victory). BG3 chooses to virtually do away with sleep restrictions. This has the benefit of enabling a permutation-powered story because it allows resting anywhere. It was at odds, though, with a story stressing urgency because it allows resting anytime. This seems to be addressed with the release version; this is a point in favor of your view.
Some combat changes can be seen favorably in light of your analysis. Surfaces are visual and reactive: Great anecdote fodder. Shove is kinda funny, the first time. However, I fail to see how most other combat changes improve the story in any way. In the interest of brevity (edit: lol) let's focus on jump and Gale.
Narratively, Gale is nothing if not cunning. He's planned for his own death, surely he can plan for his own turn. He has an action, spell slots, and a bonus action. The cool version of that story involves Gale flipping through his spell book to find the powerfull incantation that ends the battle. But BG3 enforces geometry and spell ranges. Gale has to make sure he can get in position, but BG3 only allows that kind of preview on some spells. Besides, he tends to stand back from the melee, and the AI knows to stand back from Gale, so he's often too far to do cool stuff. Which bring us to jump, which gives 5 feet of additional movement. So Gale jumps, turn after turn. And he's right to; he's responding to the physics of the game. I wouldn't characterize a ruleset that organically promotes the story of Gale, the Great Jumping Wizard as narratively sound.
That's not to say I reject your premice altogether. My conclusion is that there is a second force, at least, shaping the design decisions behind this game. Patch 1 had many changes that seemed to justify other changes, but with the ruleset slowly reverting back to 5e raw, it's become unclear which changes were important to begin with. Hide, for example, was (is? will have been?) a bonus action. This meant the rogue lost a huge perk, which was compensated with a huge buff to Fast Hands, turning it into an extra attack, but now hide is changing back and rogues get to keep their perk, I guess? Was there any narrative value in any of this?
The simple answer, I'm afraid, is that Larian cut a lot of corners and used early access to see what they could get away with. There were definitely places they weren't willing to compromise. Fully animated dialogue was one (yay for narration); game systems was not (yay for development efficiency). Think of the fact that the interrupt system (whereby a popup asks to spend a bard die or some such) wasn't in development this time last year. Only did a good deal of grousing from the community change Larian's mind after patch 8 (of nine!). Think of the fact
there's no day/night cycle. Where's the narrative value there?
In conclusion, while I concede many design decisions to your column A: "Things Larian did to enhance the story", I still see a fair few decisions fall under column B: "We made it like this in the first place; what's done is done".