I'd rather have more cities, spread more evenly over the in-game environment than for each city to be larger, or for there to be more wilderness.
What I'd also like, and this isn't really a complaint about any of the previous TES games, is for there to not be much of what one could call an invisible-but-very-obvious line between civilization and the wild. You know what I mean? Where you step outside of a city's walls and all of a sudden there's no people anywhere, just animals and monsters? In Oblivion it wasn't bad, and even in Morrowind I didn't notice for the longest time, but it could be improved.
Of course, as with many other aspects/features, the choice of location for the next game is key. Morrowind, for example, is/was harsh and desolate (especially now!
) and not well-developed by most standards, so getting into trouble so easily when getting right outside city limits, or even staying within them, is/was to be expected. And Cyrodiil is/was hardly short on wilderness too, albeit a different kind.
For this purpose, setting the next game in Skyrim would probably serve well, as it is, literally, a polar opposite of Morrowind, and, I imagine bears at least some resemblance to Cyrodiil, allowing Bethesda to kind of combine the two when designing the place. Of course, Todd Howard and crew picked a spot for the game long ago, but we obviously don't know what it is yet, so....