The Witcher 2 had high res textures straight out of the box. And it looked stunning with "just" DX9. Personally I don't think there is a specific feature that this game lacked which, if included, would make the game great. Its the general lack of care and/or interest for a PC audience that bugs me.
First and foremost, o/ to a fellow Eve player. I am sure you got my soon joke.
Anyway, The Witcher 2 had an engine optimized for the PC. It took every advantage possible of available system resources to make the game look amazing. Imagine how intense Skyrim would be if the dungeons FELT like dungeons, if the dragons FELT like dragons (not large bird-like AI breating fire). Imagine how amazing it would be to encounter dozens of different dragons, not just the 3 or 4 'generics' that are random (and feel the same, in my opinion.) Imagine Skyrim with the Frostbyte 2 engine. (Battlefield 3 and NFS The Run use it). In The Run, the roads LOOK like roads, not textures. The cars LOOK like cars, not textures. Hell, I had to question Jack's face in the opening movie. "Is that a real actor, or is that CGI?" We are in an age of true face melting graphics, blending fantasy with reality. Skyrim, in all its glory, feels like it was released in 2007, right after Oblivion before the PS3 was really recognized.
If the PC release was re-optimized to take advantage of all available system resources, the game would not only surpass The Witcher, but open up tons of options to modders. As it stand right now, we the community have to add in the features that were promised to us, because of an engine that was optimized for a 6 year old outdated console.