It's a shame that clothing wasn't a more important factor. I can only really think of two cases in Oblivion where it mattered: the Sanguine quest to lejawin castle (You had to dress pretty, but could still be wearing leather boots and be carrying a shield, arrows and sword!!) and the Dark brotherhood quest with the Deceiver's Finery, where you could murder everyone in the house, but had to be properly dressed to do so.

It'd be nice if the AI reacted to what you were wearing; they managed to make it so that they liked you less if you talked to them with a sword drawn. but then again, it'd probably annoy those players who don't want to change their items every time they change location (A possible "realistic" mode addon?) I know that I'd feel a little bit annoyed after a while, as its weirdly "enforced" roleplaying... which some people dislike in an RPG.

Having useful clothing to wear (Maybe certain tasks in the world require different clothing: alchemy could damage armour, so you wear "work clothes" (Caustic chemicals etc) Blacksmithing could require loose fitting clothing, due to heat etc?

Maybe that's too in depth, but the NPCs switch clothes in oblivion: fighters guild characters change out of armour into night clothes, or different attire to go to the inn etc.

If there is some sort of bardic "class"/option, wearing fine clothes to infiltrate a social environment would be perfect. It was always an underlying weird feeling that my assassin (regardless of the mixed "classes", which i found a welcome relief of the FIXED classes you usually get in RPGS) would only wear mithril armour, at all times, even swimming or when "taking time off". Hell, even doing mages guild quests, when you looked more like a tank than a mage.

Rambling, sorry!

TL; DR: it'd be nice if NPCs were more reflective of the changing environments, wearing armour, or changing into it. And it'd be nice if clothing had more of an impact beyond just aesthetic (Influencing NPC reactions, blending into surroundings etc)

like someone said above, oblivion was based in the capital of the empire, skyrim is much more rugged so (hopefully) there will be more armoured adventurer types there