So I was going through morrowinds dialouge and I ran across something I overlooked for years that I thought was pretty intersting. This gives a reason for why shops are always open and everybody is always awake in morrowind.

"Have you noticed? People staying up until all hours of the night? Walking the streets? Tradesmen open all the time? Strange. Like they can't get to sleep or something. Or don't want to go to sleep. Maybe something in their sleep is bothering them. If you follow my meaning."

so this made me wonder what other in game mechanics have a lore reason around it?

That's really a jab the game mechanics themselves then anything equating to lore. Similar to Maiq in some aspects.

I took it more as the dreams from Dagoth Ur where causeing people not to sleep. Like the dreamers.

no horses in MW because Dunmer eat them