From my observations, I feel the BG crowd not liking this game can be boiled down to:
It doesn't play like a Baldur's Gate game (non-infinity engine style gameplay)
It doesn't look like a Baldur's Gate game (has a dynamic camera, and again, doesn't look like it's an infinity styled engine at work)
They have issues with the writing (either not being serious enough for their tastes or not being up to par for their standards to be considered "good")
Besides the last one, these are completely valid reasons to have issues with this game, especially when there are modern equivalents happy to mimic this style of game (the Pathfinder games and Pillars of Eternity). They have even said they would have no issues with this game as long as it wasn't called Baldur's Gate 3, but because it is, they take umbrage with the fact that it is only Baldur's Gate in name. That's fair.
As an OG Baldur's Gate player, I do not possess the same hangups that they do. I've always wanted a sequel or re-imagining of the Baldur's Gate game but with a modern engine and with a dynamic camera, and that is what Larian is offering, but I still understand where these pissed off BG players are coming from and I want Larian to do more to appeal to the Baldur's Gate crowd. They need to incorporate more gameplay elements and more things to make it look like a Baldur's Gate game (I'm using 'look' loosely). For example, they've recently added the point and click soundsets, that is something I consider to be Larian making the game "look" like a Baldur's Gate game. As is, Larian has multiple different crowds that they have to please and that by itself is going to be extremely difficult to do.
What are you doing bringing intelligent, thoughtful arguments into this discussion? Have you seen the people in this neighborhood?
Personally I love the writing, and at least from a technical perspective I can say it is well-written in that it:
Shows but not tells (much of the story is hidden in visual cues) Limits most exposition to books Uses smart narration descriptively. Allows for an optional level of engagement and depth. Includes a lot of optional flavor story that is not directly related to the main story. Includes many subplots Strong Dramatic focus to the central story Memorable characters - even side characters (Shovel, love that little guy) Uses a lot of variation style - poetry, prose, writing, and changes in rhythm and accent.
I am at almost 1000 hours played at this point and I am still finding new things.