Sometimes I feel like I am the only D:OS2 player ever who actually liked Arx, even in the non-Definitive version. It didn't feel much like a city at all, but the interactions and the things you got to do in it were really neat in my book. I didn't really feel like Arx and the Nameless Isle had to be switched around, either - although it could have worked better if there was a pre-Nameless Isle Arx and a post-Nameless Isle Arx, or something along those lines.
It would be a bummer if Baldur's Gate ended up similar, though. It's not like Larian don't have a history of making large-scale urban areas (Divine Divinity had Rivertown and Verdistis, and the entirety of Flames of Vengeance takes place in Aleroth with a lot of places to go to). Even if some of the buildings are just there for decoration, it would be really nice for the city to feel like one this time around. They kinda had it easy back in the day with the tile-based maps that didn't have that much detail, but I am hopeful that the development time the game's taking is indicative in some way of the scale that the city in BG3 will have in the end. One can hope, if nothing else.
