I agree completely, bethesda would really lose nothing in adding both systems.
That's just lazy design.
I'm going to say it: both systems svcked. Balls. Hard.
Morrowind's does little to cut down on the tedium inherent in the game, doesn't have enough places to fast-travel to, and sometimes involves you having to sit through at least two loading screens to get where you wanted to go (don't throw "immersion" at me, there's nothing remotely immersive about that). But
Oblivion's swings the other way, you can go to any place you've discovered, at just about any point or time (while in an exterior location, anyway), at absolutely no risk to yourself. It's a cheat, plain and simple.
Me, I say if there's going to be a fast travel system, it should be akin to the first two
Fallouts. You can go anywhere on the map you like, any coordinate or specific location, and you'll reach it in a matter of seconds. But you do so at your own risk, for random encounters with hostiles are possible, and unlike "regular" traveling, you won't be able to avoid these fights nearly as easily, and you're more likely to find yourself in a disadvantageous position. And like any well-built world, some areas of the map will undoubtedly be more dangerous than others, and going into them unprepared/underleveled is going to get you killed fast. And that solves the issues with both
Morrowind and
Oblivion's respective systems nicely, ridding the former's tedium and the latter's cheapness. And best of all, Mark and Recall can safely be brought back without feeling redundant, and we can even try incorporating MW style travel services that guarantee safe passage that you have to pay for.