I grew up with Baldur's Gate, it (and the other infinity engine games) are very dear to me. I'm a fanboy, okay? I've played DOS 1 & 2 and enjoyed my time with them, but for me Baldur's Gate is on another level.
These comparisons are made with thick, rose-tinted glasses that warrants some context, cause DO2 is objectively a superior game to BG1-2 in every conceivable way. The original series impressed so much largely because it overdelivered on expectations relative to the simplistic game design of its day. Game design and competition has evolved significantly since then and making that much of a standout game has become almost inconceivably harder. Besides, we were young and naive back and easily impressed. I suspect most people making this comparison mostly miss who they were and how they felt back then.
First impressions from the gameplay demo.. It looks a bit too familiar. In a bad way. I couldn't shake the feeling it felt like looking at a cross between DOS 2 and NWN 2. Which sounds kinda cool and interesting in its own right, but... This game is calling itself Baldur's Gate 3. And I couldn't help but feel like, if I didn't know it was BG 3, and if I was to only glance over it and not look too closely I'd think someting like " Damn, Divinity Original Sin 3 looks really good". Which, again, sounds all fine and well in it's own right, but again, this isn't DOS 3. The over-the-top animations, the colour palette, etc.. Can't say I like it a lot. I don't mind it in DOS, but I don't love DOS. This isn't DOS, this game is Baldur's Gate 3..
This is a common complaint, mostly bundled in with "muh RTwP-combat" (which I suspect, more often than not, is a cover for "I hatez turn-based combats" which again ignores that D&D 5e is a hugely complex system incompatible with RTwP-combat). I never saw anyone even attempt to give a proper objective reasoning for their sentiments beyond it looking too much like DOS. Surely it's not the 2D sprites you crave for! The NWN-series that followed BG1-2, was a huge letdown (NWN2 in particular), so I can see why you would make this comparison when holding the original series on such an unrealistic pedestal.
Now this BG 3 isn't gonna be anything like we might have imagined a BG 3 being like, 20 years ago. Or 10 years ago, even. This is still gonna be a Larian game. And I'm ok with that. I might prefer realtimewithpause, etc etc. And I'm fine with this game being TB etc etc. I'm at peace with those kinda things. But I hoped the game would ooze a little bit less DOS, and feel a little bit more.. new? And same? New, but playing on the nostalgia strings in just the right ways. Modern, but respecting its roots. Fresh, but in touch with its legacy.
Bioware themselves doesn't make games like we might have imagined in much less time than that: From BG to NWN to DA:O to DA2 to DA:I. All hugely different games. In a way, you criticise the sequel from another studio for not being the same and being the same simultaneously. Larian has promised to play on the "nostalgia strings", but expect that to be in the storyline as it should and not purely in a game design sense. Do not expect too much of this to be spoiled though. But let's look at a couple of aspects: The
storyline is roughly similar in obvious ways; from Bhaal-spawn with unique powers changing you from within, to "mindflayer-spawn" with special powers changing you from within. The
party interaction of BG3, which was what made BG1-2 come alive for me more than anything, has promise to overshadow the original. The intrigue of draining your party companion(s) of blood alone shows this clearly, and this is but one small part of several unique origin stories and unique "generic" stories. As for
cameos: Volo is returning. Minsc and Boo spent the last 100 years or so petrified and is alive in the setting. I would be surprised if everyone's favorite drow, Drizzt, won't make a reappearance. Same for the underdark with their mindflayer colonies (though maybe for the sequel I suspect is coming).
One of my biggest worries (and still is, a little) was that we'd get a great game, but it'd be DOS 3 with some DND injected into it and a coat of Forgotten Realms paint on it. Potentially a really good game, but not quite... Baldur's Gate 3. And this worry of mine isn't dispelled completely. I think they could do more to leave some of the DOS DNA behind and make BG 3 it's own game. Of course Larian tapping into what they do well makes complete sense, and of course some things in DOS can work quite well (with more, less or no modifications) in a sequel to the Baldur's Gate games.
They can still work on the presentation of the game, add that little bit of dirt or whatever, that bit of extra "weight" to the animations, or somesuch. For example I think the UI could improve, it could look more pleasting to the eye (particularly from a nostalgic infinity engine point of view) while simultaneously supporting all the needs of a next generation Larian Baldur's Gate game. I'm a sucker for the beautiful hand drawn portraits, myself. Pretty Please?
If you have seen the demo and Q&A, most of your points are addressed. Larian mentioned developing a system for dirt and grime for characters. The UI is pre-alpha, but vastly superior to that of the infinity engine which didn't even feature a mini-map and would be way to simplistic. It is less intrusive, yet much more detailed. DOS has custom portrait mods and given it was part of the original series, we can expect that to make a comeback.
My advice would be to knock BG1-2 off your pedestal to where it belongs and stop worrying so much. You are setting yourself up for disappointment over pure nostalgia. Ironically it sounds like you would prefer Beamdog studio who has made the enhanced editions of the original series to do the game. They would give you everything you verbalise, and you would have been utterly disappointed with the result. Careful what you wish for, huh? Larian has promised to make this YOUR adventure, but their campaign which will have an appropriately darker theme than the DOS-series. And they are working closely with WotC to make it authentic.
The one and only real concern I have, is how well the hugely complex pen and paper/dice system translates into fun gameplay. But even there, things like the animated dice roll on special occasions, creative use of Mage Hand cantrip to push foes off of ledges sounds like a lot of fun in a game that promises unparalleled verticality unlike the flat-earth of the original series.