The main problem I have with Oblivion's fast travel is that it's unimmersive. It has no explanation, no downside, and you can use it from anywhere to everywhere.
You have been, and Why shouldn't I be able to use it to anywhere, Fast Travel is only a mechanic for the player, not the character. In Oblivion you were walking, that is the explanation, I refuse to believe this is coming as a surprise to you.
Morrowind's fast travel system (also called transportation system) solved these problems.
There was an explanation - travel services (Silt Striders, Mages Guild teleportation, boats; also mark/recall and intervention spells existe; To note is that the Silt Strider can possibly be replaced by a Mammoth)
There was a downside - costs of money by travel services and costs of magicka by mark/recall and intervention spells.
You couldn't use it from anywhere to everywhere - travel services (NPCs) were on specific locations near towns, which only took you to specific (often nearby) towns. Mark/recall took you from its own spot (self explanatory, but from anywhere; making it a good option when you were tired to walk back) and intervention spells (Divine or Almsivi) or a took you to the nearest Imperial Cult shrine or the nearest Tribunal Temple (this location can be changed though to something logical and suitable for Skyrim).
That's all fine and dandy for explaining how people travelled around, but it isn't good for tying a mechanic to, which is a mechanic only for the player. I like playing barbarians who hate magic and generally scuff at mages, but in Morrowind I have to learn mark/recall because I don't feel like wasting time, my character wouldn't give a rats [censored] about walking everywhere, but because I the player, is forced to stay with the character real time, it becomes a hassle to play such a character, which it shouldn't.
The result of this, is that I find Morrowind's fast travel system more suitable for an open-world RPG like The Elder Scrolls series. It has some possibilites and some restrictions; and I feel that it is a nice balance between hardcoe (travel services) and casual gameplay (mark/recall and intervention spells).
Why am I forced to use magic, mark/recall/intervention spells aren't even real Fast Travel, they are spells which as a side effect functions as Fast Travel.
Another possibility is also to keep Oblivion's fast travel in the game, while also including Morrowind's fast travel system. My guess is that this would please both crowds, and it would be, from an utilitarianistic point of view be the best solution.
My personal recommendation is that there should be a togglable option for Oblivion's fast travel system, because I believe having two systems that accomplish the same thing simulatiously, but in two completely different ways, is breaking logic.
No argument from me here.
The real question is therefore not about resisting a temption not to use Oblivion's fast travel system (and to walk or ride a horse instead), but to improve and change the foundations of how to travel in the world to what I believe to be a more immersive way - a way that gives you an explanation, a downside and where you can't travel from anywhere to everywhere.
I don't understand the need for explanation, the only thing it needs is random encounters, which would be more immersive, and function as a down side. However I still feel one should be able to travel anywhere and everywhere provided you've been there already, there's no reason not to.
"They have taken you from the Imperial City's Prison, first by carriage and now by boat. To the East - to Morrowind. Fear not, for I am watchful. You have been chosen." - Morrowind
Presents of boats and carriage would be nice, tying Fast Travel to them is debatable depending on how it's implemented.