I was trying to explain this to someone on the fallout board.... I think it comes from how and why we play games. You and I might play the same game and we might both enjoy the same game, but we can still be playing for very different reasons. From the moment PCs were invented people (nerds, if we're being honest) were trying to recreate the best of D&D-style PNP games. PNP games are only limited by imagination, but as computers have advanced we get ever closer to that ideal - the ability to live a virtual life, exploring and contributing to a virtual world.
Ultima, Fallout 1/2, TES, Baldur's Gate, Arcanum - all have given us worlds to explore, NPCs to meet and, at the end of it, our own unique tales to tell.

What I'm trying to say is that some people play 'games' while some people explore virtual worlds.
I'm not saying one is better than the other. Both groups can play the same RPG, one group roleplays and the other grinds through quests - we all have a great time.
It's also the reason that the FO3 vs FONV rages on - FO3 is more 'game-y' while FONV is more of a virtual world. They have a lot in common, but they are very different experiences at their heart.
I'm so excited to have the world of Skyrim to interact with and explore. Can't wait.