Thanks for your answer Etruscan, and I agree with all of that but most of that can be done without a day/night cycle.

Scripted night sequences for certain areas or certain parts of the story can also achieve that without needing an "open world" day/night cycle.

Originally Posted by Etruscan
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.
This is the one exception of course. I quite enjoyed the day/night cycle in Metal Gear Solid 5 for this reason.

Still, I'm not confident that the benefits outweigh the cost. I'm not against the idea though.