The primary gameplay detraction created by the removal of Levitation for me is simple -
No third dimension.
Of course the game will still look excellent and all, but the 'feel' of vertical motion in the game (adding a z-axis to the world) truly added a lot to gameplay experience. So all those people/objects/buildings in Morrowind not only
looked 3-dimensional, but could be viewed/fought/experienced from above as well. And the Superman rush of blasting through forests and over mountains, or swooping down on a monster from on high at 90 mph...
Highly cool. And, unfortunately, highly dead.
Cheers,
Michael