Actually, they did size down skyrim. A lot. Skyrim like most console games does a bit of trickery to hide shortcomings.
The textures are really low-res.. and all the other maps including alphas and bumps and such are REALLY lo-res. As in, under 100 each way. Ever wonder why faces looked so ugly? That's why, they're a lo-res and mirrored.
There's the hi-res textures patch Bethesda released which replaces it with their higher-resolution originals. It fixes stuff. However, you still find out how low the game is even with if you look. The reason it's tough to notice is the fog. This game has tighter fog than an old 3dfx era game. If you fiddle with the fog settings you'll notice how lo-res it is... the game past right up near you looks like Oblivion levels. Which is kinda sad. (Oh, and the fog is also related to why the water has a visibility that made fallout 3 look crystal clear).
But like all those games, coming out on the pc means you can patch them a bit. ENB series is famous for post-processing for many games, modders here are finally putting in stuff removed like day cycles, some tuning, and there's that hi-res texture pack.. and hardware has long since outstripped consoles with a lot.
Of course, that's how it goes. The bubble will pop soon enough though and pcs will come back into 'vogue' as the development platform. Can't come soon enough... I'm a fan of Thief games and Thief 4 is in development.. after how crippled 3 was to fit on an xbox (those tiny tiny levels? Because of memory limitations) well, I'm worried the 4th will be crippled the same to fit on a 360, and not just graphics wise but control and otherwise.