Had they just said "here is a game in the forgotten realms" it would likely have gone down better. So yeah, I agree, they should either go properly d&d or they should just make it clear it isnt a d&d game really.
I don't know about that. It certainly would've been better from my pov as an FR setting fan first and foremost. But I think BG3's draw for quite a number of people is in fact that it is a D&D 5e game that hews close to the D&D 5e PnP experience.
