Same deal with the Dragon Ages where areas had a fixed time of day. I would've preferred a proper day/night cycle but at least it gave an illusion that there was one, kinda sorta.
Kinda sorta, yeah...
The thing that gets me is that they keep on saying this is D&D 5e but the more I look at it the more I see divergence from the system. While the day/night cycle might seem completely irrelevant it affects other things. If you remove that you're basically removing the exhaustion mechanic (and one part of why rest is important), which in turn affects spells like greater restoration. I personally prefer to be drowned in spell choices (as is the case in D&D 5e) than to have it dumbed down to the point where I'm always spamming 1 spell and never looking at any of the alternatives.
From what I've seen so far I doubt a bunch of well developed D&D mechanics like turning to stone, curses or poisoning will be placed in the game either. I like that the game is story driven but I think they've made some massive mistakes, the main one being that they said it's the 5e rules while they're too afraid to actually implement them. Simply never saying that sentance would've made my expectations for the game completely different and I could've gotten behind almost anything.
It's not because there is no day/night cycle that exhaustion won't be in the game. Exhaustion has nothing do to with day/night cycle in 5e. It's tied to using Forced March for more than 8 consecutive hours and special abilities/hazard/extreme temperature exposure. Forced March will probably not be in, but the other things might be.
It was confirmed that you will need to rest in the game, for both mechanical (regain spells/HP) and story reasons. There is a passage of time in the game, it's just not a full simulation of a day/night cycle.
Also, Greater Restoration is used for other things than regaining a level of exhaustion. You're brain process of equaling no day/night cycle = no curse or petrify is super weird. DOS2 has permanent curse status and petrify that required very specific abilities to remove.
