Making a DLC for Baldur's Gate 3 would be „boring” for Larian Studios. „What we're doing now makes developers way more happy”
Baldur's Gate 3 hasn't received any expansion because Larian Studios considers making them „boring.” The devs prefer to release additional content in the form of big updates.

We have Baldur's Gate 3. Considering the huge success of the game, this could have been quite a disappointment for many players. Swen Vincke itted that this happened because the devs find developing DLC simply "boring."
Making DLC is "boring"
In an interview with GameSpot, the head of Larian Studios mentioned that the team doesn't work on DLCs, as they prefer to release additional content in the form of big updates. He considers the creation of expansions to be "boring," and the studio doesn't have the "ion" for it.
You want a happy player and happy business, but you also need to have a happy developer. What we're doing now makes developers way more happy. We had a huge hit, and people said 'DLC this' and 'DLC that,' and we said we'd make DLC, but then when we had a moment to think, we asked ourselves, 'what are we doing?'
Although many players would like to experience more adventures in the world created by the studio, it must be itted that the lack of DLC seems better than forcing something. The success of Baldur’s Gate 3 comes from many factors, but one of the most important is definitely the developers' ion for their work. If that was missing and the studio forced itself to create a DLC, its quality could disappoint many fans.
However, since the release of the game, Larian Studios has significantly expanded Baldur’s Gate 3, releasing as many as eight major updates. The last one, also ending the development, launched this month and added, among others, 12 new subclasses.
I think there would be no problem finding publishers who would sell such content separately as DLC, yet the Belgians decided to make it available for free. In this situation, it's difficult to complain about the lack of a larger DLC.
We might get one in one of the Larian Studios projects. Right now, two are in development - the first will launch project codenamed Excalibur.