Internet consumers expect to order product when they want it, at that moment.
Pre-order is an afterthought because digital inventory is infinite and the purchase can be made instantly on the go.
The pre-order is merely a reminder or a check off the buy list. For example, those whom pre-ordered the Steve Jobs book on Kindle did so to just get it done; the book will download as soon as it becomes available.
Pre-order for physical goods Is based off limited inventory and first come first serve. Digital pre-order means we no longer have to wait in line.