Clothing is extremely important. A mage that chooses not to wear armor will be wearing clothes, not all mages want to wear robes (Unless they are awesome this time) and so some decent clothes are rather important that way. It's also an important factor in roleplaying, while my hardened mercenary would be wearing leather armor at all times I'd still like to spice things up by putting on regular clothes for a change, or maybe a hooded robe if I'm trying to keep a low profile.
I agree with these things, but clothing isn't just important as an option for the player. Because even if you end up never taking off you're armor, you're still going to see NPCs wearing it. So getting the look of clothing right is important for keeping the feel of the world. There should be a wide variety of clothing in the game, whether you want expensive clothing or cheap clothing. And some clothes should look functional, while some should be more decorational. And of course, this being Skyrim, I expect to see quite a few items of clothing that look like something you'd expect to wear in a cold climate.
think they did that so you couldn't have on sets of enchanted stuff. like 100%shield and 100%spell reflect, ect
You can't get 100% shield in Oblivion anyway, since armor rating is capped at 85%, you can get 100% reflect spell, though, and chameleon, and if not wearing clothing under armor was supposed to prevent that, it really didn't work. But I think it was more intended to make unarmored characters slightly less penalized, I mean, not only do they have to suffer less defense due to lack of armor, but they also get fewer enchantment slots in Morrowind. Of course, if that was their intention, it still didn't work, because they also decided to remove unarmored gloves and the unarmored skill, meaning unarmored characters are still penalized. I mean, sure, the unarmored skill didn't actually work in Morrowind unless you wore at least one piece of armor, but that was clearly a bug and could be avoided in a new game, so it doesn't constitute an excuse to remove the skill.