In the past years, if you wanted to play a RPG, you had to choose between a game with good production value but shallow depth or the contrary. The true game changing argument this game has is that it simply has both.
No, BG3 *is* the poster-child for high production value but shallow depth. Diluted 5e mechanics are as shallow as one can possibly get. The only next step below is no mechanics at all.
Oh, and D:OS mechanics are no better. Just load up on a couple of key ranged abilities on every single party member and then pew pew pew. That's the game.
You are talking from the point of view of a CRPG veteran, of course BG3 will feel shallow to you. This is an extreme stance when you consider that pretty much no one has played this genre before. At best the most in depth RPG most people have played is maybe Elden Ring, Skyrim or Witcher 3, games where you can cruise through by casually tapping two buttons and collect generic +2 damage gear. By comparaison, BG3 is very deep, from a gameplay standpoint and especially from a narrative one with its branching story. To get back to the topic title, we can absolutely say that Larian games are "bad" for that fringe player base who takes pride in playing the most obtuse game possible. But at some point you have to realize that CRPG games doesn't have to be shackled by that arbitrary criteria, just like FPS became more appealing than Quake.