There are many mechanics that were established by BG and is standard for CRPGs that Larian chose to not implement.
Like what? I genuinely can't think of any, besides real time combat. Again i never finished BG2, it felt too clunky to play when i tried and i dropped it.
And yes, BG2 does many things better than BG3 at the moment even being 20 years old. And that is the alarming factor.
Again, like what? Give me an example.
the designation "C" RPG was literally instituted after the release of BG2 to differentiate it from the gold box and "J" RPG coming across consoles from Japan.
BG2 literally established the CRPG genre, and it's fundamentals were carried forward in practically EVERY story based RPG that followed it.
Bioware's RTwP system is the precursor to the weapon wheel, which is one of the MOST immersive additions to action RPG and FPS games in history. They evolved their RTwP system for DA:O and Mass Effect.
Literally fundamentally ground breaking game design that feulled the entire genre's development for the next two decades.
In my opinion, NONE of Larian's products has ever had this kind of impact.
