I'm actually glad Larian is looking to adapt the 5e system. 5e simply doesn't fit perfectly into video games
People talk about 5E being a system perfectly balanced over 5 years - but the truth is, the game never has had a proper "patch". The PHB was printed at the beginning of 5E and stayed the same. Aside from a few minor line changes in Erratas, all the fixes are built in supplementary material, which BG3 won't be implementing.
I don't mind adjustments to the combat system because in PnP you're used to controlling 1 character, whereas here you control multiple in most games.
I also accept the fact that 5E PnP is played in ironman mode, which alters the way encounters are designed (pnp encounters are inherently easier since there's no reloading).
My larger issue is that while I'm happy for Larian to be playing with the combat system, they really aren't taking advantage of the EA to push out quick iterations, and let the fan base try and feedback on different things. The only combat related change I think we've received due to EA feedback has been surfaces. It's already been months since the release - realistically we could've tested multiple system by this time.
The thing is, there is a perfect example of another game in development that uses the 5e system with some minor modifications (compared to BG3 at least) while being more limited with what they have to work with and the combat is much better, smoother and generally more fun.
Adjustments are fine, in some cases needed. But BG3 made changes that completely throw any balance out of the window. Combat becomes boring and tedious and generally the same (Go for backstabs and highground. That is the tactics). Which makes some classes the same and less unique, and thus more boring to play. The best way to succeed in combats is to make clever use of these added houserules and game mechanics. It caters more to DOS1/DOS2 tactics and ignoring many 5e tactics (And class abilities, spells, etc).
If you are going to do that, why even bother making it the weird 5e/DOS hybrid that tries to do two systems but fails at both. Stick with one or the other. And definatly do not sell it as a 5e game while it clearly is not this.