If you want this game to truly smell and taste like BG1 and 2 at all, and D&D at all [...]
That's the thing, isn't it? It's arguable that it's of higher priority to Larian to make something truly their own, rather than make something that "smells and tastes like BG1 & 2". It's clear to me it was never their intention to make something like that in the first place. Plenty of people don't care much for the original games, and even dislike them, as clearly expressed by some on these very forums. Hell, some have even said that this BG3 atm is precisely how a BG game should be. So what incentive would Larian have to make a game more "similar" to the originals? Why exactly should they change their design direction now? From where I see it, it's more a problem of "not wanting to do it", rather than "not knowing how to do it". From a business standpoint, it really is more beneficial to them to try to cater to as many different groups of audience as possible, rather than aiming specifically for the BG fans. This game is their big step that truly takes them as a studio to an entirely new level. I don't see why they would want to turn around and try to please the BG fans now.
That aside, it's not just D&D rules and creature stats. There's the writing and overall atmosphere, for which Larian also has their own things.
There is actually an article where Swen states that BG3 is a game that will be based on D&D 5e. They are not trying to make a strict DnD game because they want to make a game that is for everyone and they want to stick to their roots (DOS?). He also said they may not use al the rules of DnD because some of them may not translate well into a video game. He also said he is focusing on making first and foremost a video game not a tabletop.
