Preorder advantages mean that the company is most definitely not thinking long-term with the game. Meaning they know that once people really get their teeth into it, it's going to stink.
Take TF2. Several free weekends after the game's initial release, they have more than TRIPLED their sales. All those people who bought afterwards would not have the "Frying Pan of Early-Bird Excellence" (TF2's make-believe pre-order item) meaning it's an entire extra feature that only a select few get. I'm not saying EVERY game needs to update as often as TF2, but it obviously means they don't really expect their game to have much staying power once it's been out for a few weeks. I don't know about you, but if I'm going to buy a game for $50, play it for two weeks, then toss it out, then I feel I should then tear up my credit card until I can learn to spend money correctly.
I have actually shown some interest in certain games right up until the point when they say there is a pre-order exclusive bonus.