I hope you are being sarcastic.
Cost of mark/recall: Having to set the mark in the first place. Cost of magicka at least if it didn't regenerate. Typically a one way thing, you'd have to use other methods to get back to the dungeon if you require more runs. Not needed in OB due fast travel.
Cost of intervention: You may not end up very close to where you want to go. Cost of magicka at least if it didn't regenerate. Typically an escape thing to get out of trouble. Not needed in OB as you never yelled "yulp", everything was scaled.
Cost of Morrowind fast travel: Money (but cheap). Having to figure out how the routes (boats and striders) are made up, what goes where etc. Wasn't they also available only at certain days (making beds more useful)? Figuring out how the propylon chambers worked out, and obtaining the master index, it felt like a hidden quest.
Cost of Oblivion fast travel: None at all. In fact it comes with an exploit where you can ignore spells and potions running out of juice. One second feather and go everywhere - riiiiight - good gameplay!

Morrowind reduced Daggerfalls fast travel system to what it had because the game world was endlessly smaller in comparison. And it was a great decision. It worked. Most people were happy with it, or at least endured it. Once you had mapped out everything, you had done a fair bit of traveling, and you'd typically possess boots of blinding speed and had levitation and invisibility as well, reducing the need for these travel systems.
Now comes Oblivion with a slightly larger world than Morrowind. To attract more people that have no intentions of role playing but speed through everything to see the most graphics in the least amount of time - they let magicka regenerate. No cost in mark/recall, so just remove that. Levitation can't be available due town cells, so just remove that. Bah, let's just remove everything, we're on a schedule, and nobody will miss it if we make click & appear travel - great decision BGS, just... Great!

Now we're stuck with spoiled brats who doesn't even want to PAY for fast travel, I mean, wtf happened?
Fast travel is needed, nobody argues that. It just have to feel natural, like it's part of the game. It should have a cost, and my suggestion has always been to let the user choose what the cost is:
* By foot (or horse), fast or slow, where slow is safe, fast is unsafe (risking fights), and is totally free. Like today, but without the by foot exploits.
* Automatic use of found travel services which also can cost time if not open for service every day, but you'll be safe.
* Night or day or both, preferring inns or camps, automatic exploration when avoiding contact - lot's of "possible" options if you want to go all the way, but not needed for the game. Works better for larger game worlds with focus on survival, but worth a thought. Day and night might be worth it for a vampire player. Hook it up with seasons (longer or shorter days) and it becomes even more important.
That will be the fast travel options. Hard core players like me will typically use travel services manually like we did in Morrowind, and occasionally use fast travel system for multi runs. But when I'm using it now, it won't feel like I'm cheating, since I'm setting options if I want to travel unsafe and risk a fight, or supersafe and pay with money and time. Paying with money and time may not be the best option if you're on a time limited quest. I can naturally also do it completely manually and walk/ride if that is my game.
I can think of many quests that over time improves the quality of fast travel services, like i.e. you have to clear a route for bandits and bandit camps before the route can be utilized, or running around hiring riders for dilligence services so they can be open for business more days in the week etc. It improves the living world we play in, in that what we do affect what we can use. Maybe after some time, some other adventurer did it instead? Who knows... Endless possibilities.
---
The Warp point sounds interesting. It could replace the propylon chamber system, or just add to it. But it shouldn't be the only fast travel system in the game.