The zombies, murderous orcs and evil cultists would apparently leave you alone... for some reason?
1- maybe I am invisible, or sneaking, or disguised, or spell shapechanged. But this is not the point.
2- The point is it sounds as stupid to you as killing every cyseleans I am supposed to protect, and then whinning because I can't fulfill the quests sounds stupid to me.
So wasting to much time for either things is stupid.
On the other hand, day/night cycles are not stupid. They are part of any remotely realistic RPG.
Can you imagine Larian offers some players the possibility to kill every NPC around, and no D/N cycle ? And those players can take their time, because actually, they DO have all day !
Larian goes to some hyper realistic empty/fill you cup, and doesn't have D/N cycle ?
This is WRONG.
Just reducing the vision at night/adding some light effects could make a nice feature.
Unless, of course, there are two exacly opposites suns on this fantasy planet, so there are no day/nights... But that sounds a bit of an overstretched explanation.