Day/night cycle could be worth addition if there was something behind it. Like bandints and monsters appearing in some parts of the world at nights (not entirely random on the map but ambush in places where it has some tactical sense). Making day/night mechanic just for having it is a waste.
This is such a weak argument. Both because wrong in general (as already said a basic implementation would be already massively better than no implementation) and because generally short-sighted about the possibilities the feature opens.
It goes without saying that once you had a basic form of passing time-day/night cycle implemented in the game then content deliberately tailored around it would come, because you'd be giving the designers a pass to use the feature.
Conversely, to keep rejecting it because "You either DO A LOT with it or it's not worth it" acts as a complete showstopper to begin with.
It's like not putting a wardrobe in your new apartment because "You don't have that many clothes anyway" and then from that point going on you keep hanging your three pieces of clothing on a chair and every time you are offered a choice to buy some more you'll keep rejecting them because "you have no wardrobe, so there's no point".