Weren't walled cities the one of the reasons for excluding Levitate in Oblivion?.....and those are back in Skyrim, so yeah.
No there was other issues also
-Speed tree has bad LOD visuals when you hover over it, since its middleware devs doesn't change it too much
Skyrim has entirely new new technology for trees
-LOD textures have noisy view from high altitude
Skyrim has improved LOD technology thats can handle it, as well thee is new mountain mist effects thats hide many artefact's and make mountains more realistic
-Pathfinding issue, when AI doesn't have enough pathgrids he cant orientate well in area
Skyrim has new pathfinding technology
-AI incapable use levitations in Oblivion
Oh well even mods fix this in Oblivion, in Skyrim we have flying creatures, I don't think dragons so easily will lose their natural advantage in combat with non-flying enemy thats urological for intelligent being, as well I don't think only dragons inhabitant skies in Skyrim.