There is a way for DLC implementation to be a great thing. Looking back there was a wonderful Super Hero game, Freedom Force. The game was well designed and would have been very successful as a "service". Imagine that every 30 to 60 days a new "issue" was released which was part of an existing campaign or part of a new campaign. Periodic game engine updates would be included. You paid a "subscription" for the new issues or paid a higher fee to buy them Alacarte.
Now take the ideas presented here to the same progression. Various Forgotten Realms modules or even other world modules, could be made into mini downloads for BG3 and it's system. These could be low cost items to just add more play options. A deeper new campaign could be developed over time and made available later.
This approach means the game has a longer life and potentially better cash flow for Larian. For gamers it means they can have steady content, potentially at a reasonable price and with few delays. Imagine if Larian did not need to "re-invent the wheel" as it where for a new game. Instead could just commit resources to a new campaign storyline, new (as needed) art work and dialog. By keeping the base of the game the same of only mildly upgraded, they could reduce the "next" games production time and lower the cost.
This approach brings all the cool potential of a DLC to the table with none of the downside. The bad of DLCs right now is developers use them to add material to the game that they already often had near ready, just decided to hold back for cash. The approach we are discussing is expanding on the exiting base with new material outside the scope of the original game and storyline.