First off, excellent post OP. I very much agree.
Story and characters are secondary to gameplay and mechanics. It's a videogame, not a novel (or even a movie).
That being said, I don't think Larian are the best story tellers.
It is a role playing video game. How can story and characters come secondary to mechanics?
This is it exactly for me too. In a ROLE-PLAYING game, story, characters, character development, and yes even lore are what matter. Mechanics are just a means to an end and nothing more. And I think that ultimately this is the fundamental divide among people reacting to BG3: those who care about BG3 from a (D&D 5e PnP) rules and mechanics standpoint, versus those who care about it from a story/characters/lore standpoint. Both of these things are necessary for an RPG to work. My point is about on which side of this divide the focus of the developer falls in creating the game. And because this is what WotC wanted for this particular game, Larian's focus is on the rules and mechanics side of things far more so than the other side of things. I am not that excited about BG3 precisely because I only really care about story, characters, and lore, and as things stand right now the game is rather weak in those areas. As far as mechanics are concerned I am firmly in the camp of Larian freely changing as much of the D&D 5e rules as they need to change to make the game a fun VIDEO game.