One of the most hillarious comedy-reliefs in Morrowind was all the naked nords. One being paralyzed by a witch, one being angry at you for you believing something was wrong as he just enjoyed standing there naked in itself. There was more encounters like these but the naked nord standing around with some related quest or humorous banter was one of the "little things" that made Morrowind great.

How come I havent found any in Skyrim? Did they forget about them? Did they want to avoid overusing the humor because Skyrim was meant to be darker? Or did I simply miss them?

Nope -- none in Oblivion, either. I think that was just a Morrowind thing.

Besides, in Morrowind's heat Nords can afford to be naked. It would be much too cold for that in Skyrim.

Sometimes, When I come across the 3 Revelers, one of them is naked, also, sometimes the Couriers are naked as well.

This.
The joke is still around though. Just sometimes people didn't noticed it.

There are naked nords in a hot spring near the Eldergleam Sanctuary