Levitation should only be a tool to get to places you normally couldn't not something where you can fly all over the world, which is not supported by any lore.
Again, you're going to have to explain this one.
Simply because it nowhere explicitly states in some in-game or out-of-game text that "Oh, btw, if peeps have enough magicka or ability or what have you, it's perfectly OK for them to use levitation as much as they want," doesn't mean in the slightest it's unsupported. If there is a presence in the world that is powerful enough (and seeing as I became a God-Killer in Morrowind, and that we pretty much should be considered a foretold God-banisher in Skyrim, I think that test is passed), then they should be able to channel raw creatia however they please. This can be gathered not just from in-game texts detailing all the comparable magical happenings since the Dawn, but common sense regarding what was presented in-game.
Never mind that a simple half-baked potion in the Infernal City reached from distant land to the underbelly of Umbriel. And that was probably no small distance.
I'll understand if levitation isn't added for gameplay structure reasons, or time constraints, or if it's gimped for structure or style reasons, but trying to pin it on non-lore support is just silly.
Cities are going to be in their own separate cells and having levitate would mean you would be able to see the big empty spaces where towns are supposed to be.
Unless you've got a reliable link, no dice.
If it's a "There's no way they're going back to this style," then there is one very easy solution: Umbra - Occlusion-culling middleware that allows the game to not render anything that is not within the player's vision. Or, if they didn't want to license it, just like they're apparently not licensing SpeedTree anymore, who's to say they didn't create their own occlusion-culling support just like they did their own tree-support?