Honestly, if they didn't want to program "Time" they could still set up a nighttime variant of the map by having us toggle the end day thing and then traveling out into the area. Creatures could move to a different position for night and have different nightime actions like sometimes sleeping and sometimes night will be more guarded, and perhaps different quests and characters will appear or be progressed. While this suggestion might be janky, it would just amount to a day and night toggle that adds some more depth to the game.
For all we know (and I suspect it will happen), there will be instanced night missions etc in BG. Considering your dealing with vampires. But a full day/night cycle, I just don't think will be in the cards. Or maybe Larian will pop it as a surprise, but I doubt it.
