Oblvion: Procedurally-generated landscapes created via algorithms, which was then haphazardly "looked over" by a handful of world artists.
I'd say they went back to randomization, and they need to get away from it again.
Procedurally generated seems the right way to go to me. Like people have already said, there is a lot of awesome tech for random land generation out there. Oblivion's tech for random generation was just really bad... how the hell were caravans meant to travel along those roads!?
If the land was randomly generated every time you stepped outside a city, or even every time you started a new game, then the world would lose its charm. We need a huge world that we can explore to our heart's content, and with enough travelling by foot (rather than by fast-travel) we can learn the wilderness areas by the backs of our hands, just like any NPC hunter from the area would be expected to know. Take the Imperial Reserve south of Chorrol for example. I know that so well from all my shortcuts to Anvil that it has a sense of personal familiarity about it. I know this area better than most, and that thought feels wonderful. I put in the time to learn the lay of this land. If it changed every time I wandered across it... that would ruin any sense of immersion.
Ideally, imo, the world space of TES:V should be as large as possible, built with a GOOD procedurally-generated land technology, and then looked over
properly by the world artists. And for the love of Dibella there had better not be any more 45+ degree road inclines.