I think the better question is why are we getting any DOS stuff at all? I own DOS 2 and enjoyed playing it but I have no interest in introducing Divinity content into BG3, it seems like cheap advertising or an admission that they really wish they had made DOS 3 after all.
This... so much this. I honestly don't want to see any DOS content in BG3 as it breaks immersion. They seriously need to reconsider not doing this. The worlds are different, the rules are different, the story-line is different, etc... DOS and DOS II are just "ok" games after playing them both (hated the linear, cant go back story-line which made it a closed world, not open). BG3 needs to be more "open world" and allow us to travel back to places we have been. Such as once we are in act 2, allow us to travel back to act 1 region albeit changed as it may be from actions in act 1, to chat with NPC's there. As that would allow for a more immersive feel, like bg1 and bg2 had. Mind you there may not be much there to see, but at least one would have the opportunity to do so. But that is a topic for another thread altogether.