BOTH!
Weather it's spending $30 at a used gamestore, or fullprice at a big-name retail outlet, we are the customer and we deserve a product that works AND looks just as good as the other console.
Are you a child? Do you understand *anything* about graphics hardware, how code is written, graphics libraries, etc?
All hardware is not created equally, and a PS3 is NOT a Xbox. They have different hardware and different capabilities. The Xbox will look closer to a PC, because it's based on PC hardware.
Even if they wanted to, Bethesda could not make the two versions look just the same, because they are running entirely different hardware. Sorry if that offends your delicate sensibilities, but it's the real world. You can't get blood from a stone, and you can't make hardware have capabilities it doesn't have. The design team has to balance how the hardware performs with the graphics features they'd like to have in the game. Would you be happy if your game looked like a movie, but had a framerate of 2? You can't have it all, everything is a trade-off.
If you Bethesda came out with Skyrim for the Gameboy, would you expect it to look and perform just the same as on your PS3?
Grow up already.