You've made quite the generalization based on one example of a real time MMO. I still acknowledge the artistry behind it in the case of DayZ, and it's even more interesting within the context of Kojima's career.
If the game was designed for it, I could see the advantage of having a synchronous day/night cycle in game for a few reasons.
For instance, an RPG where your time of day combined with in game locations could change what enemies spawn, or characters that get sleepy and less capable after so long, but it should also be able to cause unique time events to happen, and not just spooky Halloween season or Xmas spectacular, either.
