There is a simple reason they must deesign for the xbox.....if they didnt the xbox version would be more buggy then a house of cockroaches.
Xbox has the most limited hardware, designing for it first means that the game will run on every platform with equal or more hardware (PS3, gaming PC etc). It much easier ot covert a game up in power then down, so all companies releasing on all platforms start with the weakest one first then port to the others.
The whole reason behind having a gaming PC for skyrim is the same as with Oblivion, you get mods later on to raise the graphics to insane levels.I dont expect thme ot build a game to match my PC, but from past games, I do expect them to let me mod my game to match my PC.
PS: And anyone that says that they refuse to play PC because a controller is more natural........by a compatible Xbox 360/PS3 controller for your PC, then plug PC into TV. ta da....PC that acts like a console....only much more powerful. WIth any luck bethesda will provide controller support with thier game again (like they did with fallout 3) where the xbox 360 controller will be supported by the game on PC rather then just manually rigged to the controls by the user.
EDIT:
I don't see what the big Console Vs. Pc deal is. I've seen the Crysis, which probably has some of the best graphics as of now, on my friend's amazing PC rig and I honestly can hardly tell the difference from the PS3 version.
Thats a bit hard to do seeing as the original crysis wasnt released on consoles. You are talking about crysis 2, which was PC port from consoles. The original crysis can still match game graphics today.