It would be nice. And funny to hear, too.
Imperials in Morrowind: "Oh, you are naked. Spare me!"
Or Altmers: "Been some time since I've seen one of those."
:rofl:
But yes, NPCs should notice your appearance: so, they should react somehow if you walk around naked.
Problem with how Morrowind handled that was, it had a variable checked for in dialogue filters. That variable, though, just checked for the total value of things you were wearing. Since a ring had the value of a common robe, equipping a ring and walking around in your birthday suit made the game think you were dressed.
Also, that variable wasn't used too often and so NPCs rarely reacted to your clothing. Other than a generic greeting here and there, like "I see from your outfit that your affairs have prospered"...