The essence of baldur's gate is its dark fantasy universe, its dungeon and dragon sides, its narration, its feeling of freedom of action to make a quest, its characters with whom you can create links.
You just described most of the D&D rpg games that we had. NWN, BG, IWD, Torment, ToEE, etc'. The reason each one of this games had a different name, and not just Baldur's Gate X, is because the story was different. Yes, Baldur's Gate is an rpg based on the rules of D&D, indeed this is the truth. But not every rpg based on the rules of D&D is Baldur's Gate. We can't just call every D&D game out there Baldur's Gate just because it's an rpg with D&D rules. Imagine reading a story with three chapters. The first two chapters tell a full story from beginning to end and then the third chapter is something else, 100 years in the future, different characters, and even different writer and writing style, but it's a fantasy story about D&D.