I haven't played 1 or 2 at highest difficulties, if I ever do, I wouldn't be surprised if a lot of this is true.
endless and incredibly dull ruined city soviet levels
My memory of the CoD 1 campaign is,
-Handful of Band of Brothers style missions in Normandy, assaulting/defending town, plus a car chase level
-Several commando style raids with a small team (chateau, prison camp)
-British commando raid on the dam where you go in solo, followed by a couple chase levels plus the battleship infiltration
-Soviet campaign where you start without a gun, then end up sniping a lot. Good mix of big battles and tense solo traversing Stalingrad
-Soviet campaign also broken up by tank levels
-Big finale level for each nation
It's a lot of variety and a lot of levels that are distinct and memorable. I'll grant that UO is full of big setpiece battles that blend together more, but it still has cool shit like the Dutch resistance mission and Sicily SAS infiltration.
In CoD 2 there's a LOT of snowy, bombed out cities (already done in CoD 1, would have been cool to do something different with the Soviet campaign), and a lot of bombed out French towns. The North Africa missions stand out as being the most memorable. But there's less variety overall in gameplay scenarios.