It's harder to make a TES Demo, unless they only let you play in one dungeon, which would give you a false impression of an open world RPG. ;) The reason is exactly that it's open world, in which a demo would demand a lot of work for the developers to make, instead of spending said resources on making the actual game. It's possible, but much harder than for "closed off" worlds. That and if it were simply a timed demo of the game then it could be garunteed a majority of the games secrets would be discovered before the games release. Not to mention the amount of people who would play the demo and become instantly hooked on Skyrim. Bethesda could possibly use a Demo like a propaganda tool? Bring back the gamers lost to COD and so forth. Can you imagine the amount of people who would download the demo and play it, then immediately pre-order? They would number in the thousands, Bethesda could theoretically build a larger fanbase with a demo, but however upper comments are true. Why waste time on a demo when you could be improving the final game itself? :)