Oblivion was a anti-lore game. Cyrodiil was described as jungle region and the Empire always had a roman theme going on. So they didn't just change the look of the imperial armor, they changed it BACK.

Oblivion has hugely been effected by Lord of the Rings' succes. Suddenly Cyrodiil needed to become a copy of Gondor and it's citizens became mainly white, whereas the climate of the region (according to lore) was much more tropical and thus the Imperials should have had a tan.

Skyrim brings back the Imperials as they were previously intended. Now there is nothing wrong with letting things evolve, however the changes seen in Oblivion (which took place 4 years after Morrowind) were just unbelievable. Now they've changed things back, but this can be accepted considering 200 years have past and things should look different.

i always thought they had a roman look about them even in oblivion . the change could maybe reflect a lot of things , one is that they wanted the armour to reflect the landscape and the culture of skyrim ... might sound wierd but a few hundred years have past alot of stuff would have gone down man ... damn .... thats alot of runway shows