PS: What is it about the day/night cycle you actually like? You haven't even said why you think it matters except that "everyone else does it".
If I might hijack your question here from a personal perspective, cosmetic additions like day/night/weather add immensely to the atmosphere of a game world. In BG1 you escaped after your father is murdered on a dark, stormy night. It sets the scene strongly; would this same instance have worked as well in the permanent sunlit lands of BG3?
The city in BG2 had a wonderful night time ambience, replete with night time sounds and potential danger at every corner. Night time is the perfect time for vagabonds, thieves, vampires, etc. and the idea that we will never get to experience the world of BG3 outside of daylight hours is a crying shame to me.
I've said it dozens of times on these forums but it is an absolute farce that classes who specialise in stealth/thievery are not able to put their skills to use in the twilight hours.
These things might not matter to some or even most gamers but they were a part of the original BG games and make for a more living, immersive world.
