Levitation is really the only thing removed from TES that could be Justified ( Towns are separate cells etc.)
No, not really. There was nothing to keep them from allowing levitation inside dungeons or caves. They could easily have come up with some lore to justify it not being useable outside, such as the harsh environment of Skyrim of something else.
However, instead of slightly altering something that's in the lore and allows for some fun in-game, they just removed it (like many other things, unfortunately) and added children. Ugh.
So instead of just fixing entering towns by going over walls, which should be a trivial fix (Heck, MMOs have been handling nearly seamless zone control like this for a Looooong time...DAOC and WoW for example, doesn't even have loading screens except for dungeons (and in WoW, moving between continents/dimensions), just a momentary flicker as you approach visual range of the zone boundary (Loads both zones at the same time so you can just walk across at any point) they just removed any abilities that would allow you to do so?
-10 reality
+10 Laziness
-10 reality
+10 Laziness
Look at all they removed for the sake of making the game "streamlined" and more appealing to action-adventure fans (streamlining an RPG makes it less of an RPG, though I guess RPGs don't sell very well and games like Uncharted are cash cows).