Although unlike Morrowind, I never caught myself saying "Oblivion is too high fantasy", I still much prefer Skyrims enemies. Oblivion was spammed with magical/deadra at the most ridiculous places and made them no fun to encounter. The conjuration & necromancing thing seems a LOT more natural in Skyrim. I really wouldn't know where to place much of Oblivions enemies in Skyrim and still have it feel natural. Like Amazon Queen says, the randomness made it ridiculous. Can't understand why anyone would want this back. Also, I much prefer NEW enemies, in which I think Skyrim performs very well. It was already posted, most Oblivion creatures have a counterpart unique to Skyrim, and that's the way to go imo.
As for "cities", they're on par with what I'd expect from nord settlements in such a harsh environment. I wouldn't have accepted it for the major towns in Hammerfell, not that what I think would matter

But in Skyrim, for me, they do the trick and they work. Without proper dialogue system in place, and with the need to control the save games, I don't expect we'll see Daggerfall sized cities in a long while, if ever.