A pre-order is a sales tool as far as I am concerned. It is a better reflection on true demand for a new product.
It's easy to say "I'll take one" or "definitely on my want list", "count me in" etc etc etc. We order based on supposed demand we see online in comments such as this and only sell 10%. Not a good business decision.
As Mr Wolverine stated earlier he doesn't like pre-orders either but ther are a necessary evil.