I think that’s a bit overly simplistic. The game takes place 100-150 years after BG1 and BG2, and I like that a lot of races, particularly when you get to the city, seem to have integrated and diversified the city. The Goblins and Duergar live in isolation, so I can see why they stand out.
No, that's overly simplistic.
I can look at real life, go into cities and see various different cultures in different areas. These are based on simple cultural differences from humans hailing from different countries or regions.
Yet, in this fantasy setting,
completely different races all homogenize into a single culture? Or have very little cultural differences depicted...
Lets not even get started on the lack of emphasis on uncommon scenarios. Like how no-one gives a damn about Dame Aylin being an Aasimar (Which are supposed to be really rare), there's no depictions of tieflings born to non-tiefling parents (Since much like a Sorcerer's bloodline, such a trait can pass through generations and suddenly manifest if an ancestor had a child with a Devil - Such is the case for Woljif in PotR. But no, literally every Tiefling in BG3 was explicitly from Avernus), no notable interactions with Lolth-sworn Drow on the surface, no interactions with deities (Such as people showing adoration for their respective deities or even things like people converting to worship other deities, besides Shadowheart) etc.
People in real life have preserved cultures for thousands of years. But apparently, no-one in Baldur's Gate gives a damn about their heritage that they can lose all sense of cultural integrity in a mere 100 years...
