The lack of night/day cycle is a real heresy, a true immersion breaker. What reason can justify such a choice, except the copy/paste of Dinivity?
It's more important that a throwing of shoe IMO...
Way to be over dramatic.
Not every game needs a day/night cycle. And nothing about 'copy/paste' would be the choice to add or not add it.
A lot of presence or lack of features in BG3 have for explanation the copy/paste of DO mechanics, the day/night cycle is just a another exemple of that.
For exemple, the "Origin Companions" is a good illustration of this mindset and a result is a less immersive story for no-origin main character and a smaller number of NPC compared to BG.
You do realize a day/night cycle is one of the easier things to create in a modern engine? Not many biomes have too many different creatures between night & day in your average D&D setting (And I'm speaking of PC. A DM around a table can add all sorts of creatures).
So it's as simple as dimming the lighting over time, or setting a timer that says 'At <x>, use Dusk lighting'. 'Now use night lighting for night at <x> time.' then 'At <x> time, use the Sunrise lighting' 'Now use the daytime lighting at <x> time'
I'm oversimplifying but it's not all that difficult, compared to many other things.
The choice is artistic and has nothing to do with copy/pasting.
Edit: For a day/night cycle to be all that worth spending money & time making, it would have to have a PURPOSE. I mean, it could be fluff and do nothing; monsters stay the same, NPCs don't sleep, so you can still buy things at night.
But that would be a bit down on the list of 'things to implement', I'd think.
