When you build it as one thing, there's no way to portion off a section and have it stand on its own without putting the whole game in the demo, which we're just not going to do. And it doesn't really capture the fun of a game like an Elder Scrolls or a Fallout, where you can go where you want and do what you want. So no demo, sorry.
That is true, but credit the developers for building easy modability into their game from the start, allowing such amazing improvements from the user community.