Changing the name will be a massive improvement. The only people not upset about it being called "BG3" are people who don't know or care about the Baldur's Gate series and just want DOS3. In no way is Larian's game Baldur's Gate 3, so it definitely should not be titled as such. This is sleazy exploitation and snake-oil to max.
Here are some other possible names:
Baldur's Gate: Shadows of Tentacles
Baldur's Gate: Descent Into Avernus 2
Tentacles Over Baldur's Gate
But will Larian do the right thing and change the name? Swen stated their intention is to do a cash-grab by exploiting the fans of the BG name to try to make the DOS brand more popular - which is to say that Larian's "BG3" isn't about Baldur's Gate at all. It's just using the setting as a husk to shill for their own DOS brand:
... so, the chance to do that, and to bring what basically is our RPG identity to Baldur's Gate as a franchise was an opportunity too good to resist. And so, what it will do for us... uh, what we think it will do for us is it's going to show a larger segment of people, because I think Baldur's Gate 3 will reach more people than Divinity will have done... it will show a larger segment of the population what our RPGs feel like and hopefully bring them to play our other games also.
Larian can still capitalize on the Baldur's Gate game while not marketing their DOS formula D&D game as the third part of the original PC Baldur's Gate Series. Since Larian's game has nothing to do with the eponymous PC Baldur's Gate series, it shouldn't be named as such.
