I do worry that people will play these monster builds, then complain that encounters are too easy, and then Larian will balance off of that.
I'd be surprised if Larian didn't balance normal difficulty round single class, reasonably default PHB-type characters. Especially given that they said that they expected mainly experienced players to multiclass and weren't trying to draw a lot of attention to it in level up (which I can attest to as it's just a relatively small "Add Class" button at the top right of the level up screen that could easily be missed if you weren't looking for it. What wouldn't surprise me is if, at some time down the line, once they have had chance to see just how exactly players are able to exploit their systems to wipe the floor with the game, they add a further nightmare difficulty mode designed to make the game challenging even for those players (and probably failing, given that an engine with as much complexity and flexibility as BG3's is probably unavoidably going to have loopholes).
This is the concern, really. They start building on a shaky foundation of bad homebrew and then keep adding to it, getting further and further away from D&D.
When they should simply offer an authentic D&D experience (mechanically) and build on that. I am by no means any kind of a rules purist, but I have read the 5e rules because of BG3. Larian are like a bull in a china shop with D&D. Breaking the game with reckless changes is not going to be "better" or "fun". It feels like the changes always stem from a personal preference rather than player feedback or experience with the D&D system, or necessity for a video game.
