They chose to make a sequel to one of the most beloved rpg game in history. They realy cashed in on the name by selling incredible amount with only a alpha early access version.
However they didn’t make a game new from scratch but instead used not only the engine but also tons of mechanics and gameplay from a totally different game than the baldurs gate Games.
Is it so surprising that pisses off a lot of fans? Was that a miracle that couldn’t be foreseen?
They knew this will happen but ignored it because the financial success of using baldurs gate name is simply overwhelming and outweighs negative criticism. And by choosing divinity as a core to start from they also have a lot of divinity fans on board. From a commercial viewpoint I can respect that decision.
They realy wanted to make a baldurs gate 3 game but have no idea of DnD or what made it so enjoyable. So they got some guys from wotc as advisors (probably those who almost killed DnD when they came up with 4th edition) and then try to implement things that have proven funny with their other games.