Yes, the purists will be mad and bawl, but the reality is that 5e is not some D&D perfection - it is a ruleset that is meant to streamline a lot of BS and a lot of unnecessary rolls, checks, knobs and so on of previous editions and it's also a work in progress by the makers themselves. It's kind of funny people are asking for a faithful 5e representation with all the variants and extensions there are to begin with and changes coming up.
I do think, for example, Larian does good by changing some stuff. For example Ranger 100% needs changes and whatever they did there already was greenlighted too. And yes, I'm down with them spicing things a bit with surfaces, weapon abilities and so on - far from everyone who will play BG:3 is some purist maniac and many others will take it up and be like "why this class is so boring" when they try out a fighter or rogue, which are as basic as they get by gaming standards. So it's cool there are extra few options there whether it's weapon specific skills, dipping, illithid powers and maybe a few other tricks to spice up the blandness.
The "5E is not perfect" argument is silly at best. And in reality it is just another straw man. Nobody is claiming the system is perfect. And yes, we can ask for a somewhat faithful adaptation of 5e. The core rules stay mostly the same if you add optional rules, and saying it is a work in progress is stretching it. TTRPG's have always released new books, but they mostly add options.
That being said, I find it funny that you think 5e needs to be perfect. DoS is far, far from being perfect. And "spicing" things up with surfaces does not help the game ... people complained about the surfaces in DoS2 too. So why do you have faith Larian will improve upon the mechanics of the most popular D&D edition to date? The changes to rogue does not make the class less "boring" as you put it. How sneak attack is applied is actually unintuitive and clutters up the UI with abilities. I would strongly argue that the way 5e applies sneak attack is superior for a video game. And removing expertise from the rogue does not make it more fun either. Being a skill monkey is part of the fun when playing a rogue. Not only that, but rogue and monk also lost some of its coolness factor by giving everyone access to a bonus action disengage. And if you fear some martials will be boring, then give them more actions from 5e instead (grapple etc). And does every game need to cater to the lowest common denominator? The people who get bored unless there are tons of swooshes and bangs everywhere?
Many of the changes to the core rules have cascading effects too. Most of 5e's systems are tightly knit together, so when you change 1 thing you are going to have to change 3-4 more. At some point it stops feeling like D&D. And the balance becomes even worse than what it is in 5e. Firebolt applying damage 3 times for example. Because Wizards need help ... And look at how easy it is to abuse advantage now that they have have added facing.
Like I have written in this thread and others, I think game mode options would solve these problems. A game mode more in line with 5e rules (No surfaces from cantrips, shove as an action etc), and a game mode for the crowd that wants explosions and seas of acid everywhere. This wouldn't even require much coding.
