I get where you're coming from for the most part, other than the "toilet chain" thing I think is a bit tired and more of a nitpick, but whatever.
The four character party though, I think this really is an edition difference thing. 2E tended to have the idea (I don't recall if it was explicitly stated anywhere and I'm too lazy to go look) that you'd have 5-6 players at the table, but could have more. 5E is explicitly designed and balanced around a party of four.
Day-night cycles, sure. I generally agree, but I'm not sure how much of a difference this will actually make in practice. In BG1 it made a difference because of how travel worked and random encounter spawns, etc. BG3 seems to be a far more narrative experience with no random encounters and no real overland travel - at night you camp, during the day you move around. Any evening encounter would be handled through the camp screen which is set to night. As a result, putting a day-night cycle might be a mere cosmetic that uses resources for essentially nothing due to the difference in game styles. I take this back if they've introduced overland travel and random encounters, but as far as I know they haven't and haven't planned any which also makes systems like rest, exhaustion, etc. more or less irrelevant. I suppose this works into your "diorama design" criticism and that's a fair point.
UI thing is a matter of taste. People bitched about Solasta's UI style even though it works great and, at most, a different colour scheme may have been preferable to some. It's not the best UI ever, but it's far from the worst.
Anyway, this strikes me as generally a tension between more simulationist and more narrative style games. The thing is, I think that's less about "what Baldur's Gate is" and more about the history of tabletop RPGs and how they've really changed focus over the past several decades. Games like 1E and 2E AD&D were more simulationist, gritty, and more likely to kill off your party at the table and have that be part of the game. 5E has completely moved away from that into a narrative focus on your party of Mary Sues. This tension can be seen in all of the bitching in the tabletop threads about 5E. As a result, could Larian make a game that hearkens back towards 2E systems and feel? I seriously doubt it. Not while keeping the D&D license and Baldur's Gate name anyway, because WotC has pushed to only use current edition systems and because Swen was talking about streamlining more, not less.
Things change and have different merits. As mentioned, the systems you seem to really want are well served, just not in this particular game. If it's just that you wanted a continuation of the Bhaalspawn story, it sounds like this will tie in somehow, but other than that, why would you care about that? The story was over and that desire is how you get shit like Minsc being thrown in for fan service. 2E's time has ended and the Baldur's Gate IP is far less sacred than you seem to think. Even around when the name was still relevant, games like Dark Alliance 1 & 2 came out. Feel free to buy the rereleases to refresh yourself on what it means to have a true Baldur's Gate experience.
