It sounds surprisingly standard, more than anything.
I could go back to the 80s listing games that had something similar.
It's just Larian that seems to think you'd need to be at the cutting edge of tech to implement it.
I may be wrong but I don't believe they said it was a technology issue but a complexity issue. As in- adding day/night adds a layer of complexity to the already multiple layers of complexity they have in place. They would need to then add schedules to people's behavior, and they didn't want to do that.
Personally I would love to see it, even if they had to hire an extra 10-15 people to handle the workload and even if it delayed the game by 6 months or more. I would rather have it than not, but I don't know what the actual resource levels are.
It just feels really important to have a feeling that time is moving and to see Baldur's gate at night.