I really don't want BG3 to become a game that has the philosophy of let the modders fix it .
Modders should be adding quirky stuff to BG3, not expected to fix stuff Larian should be adding to the game.
I am sure, modders will add Artificer, UA subclasses etc. But I am fully agree with your thesis
Yes, modders can do amazing things. They added turn base mode to Pathfinder:Kingmaker which was so good, the makers of it added it to the official game.
I do look forward to stuff like modders adding Bloodhunter or other homebrewed stuff to this game. I really hope Larian adds the Artificer though I expect not, as it's not PHB.