I'm going to have to disagree with you. The landscape varies from each biome across Skyrim. Unlike Cyrodiil, Skyrim actually included a diverse providence. It almost appeared as if there was only one biome in Cyrodiil, yet it was later pointed out that there were multiple ones. Maybe I just haven't explored enough in Skyrim to start feeling like I'm hitting the same area every five minutes.

The biome differences in Oblivion were more subtle. I think I was on my third character before I properly noticed the area north of Anvil looked different from anywhere I'd seen in the game. Then again, I might have been on my third character before I walked over there at all.

I think they were aiming for an environment where everything transitioned seamlessly. It works, but makes the variation harder for lots of people to notice. Most players are used to games where the biomes change very abruptly.
Skyrim does this well too, but the differences in biomes are less subtle and there's more a sense of each region being locked into a certain season.