Totally agree with you pvtchurch.
I tend to think that demos kill more potential sales than they generate. At least for me. Personally, I can't remember any demos that have sold me on a game (maybe Uncharted and Ratchet and Clank) but I can remember plenty of demos that made me say no when I otherwise would have said yes.
At any rate, giving the demo to people who preorder makes zero sense to me. What is the potential benefit? To make them even happier that they pre-ordered? So what? The potential downside? Make them cancel or switch their pre-order to another game because it's not what they thought = lost sale. Seems to me that the cons outweigh the benefits here. On the other hand, I personally will not be pre-ordering because I'm not sure on the game yet. If I were offered a demo, I think I may be swayed (a rare thing - as I mentioned, I'm usually turned off instead of sold by demos).