What's the infatuation with preorders?

Reading articles and listening to podcasts, people keep going on about pre-orders, gamestop..etc...etc. Whats the deal with it? I've never pre-ordered a single item in my life and there is no need to. The local shops always had everything in stock day 1 without problems.
 
Let me describe the local market. You can pretty much call it a perfectly competitive market for you economists.
Save a few chain book stores that carry games on the side, we do not have any single provider of games ie...EBgames/gamestop. However, we just have dozens and dozens of independent game stores that are pretty clustered around each other in several spots around the place I live. Prices are pretty much the same so it comes up to a choice of convienence or preference. The monopoly is at the distributor level but on the retail side, it's pretty much equal footing for everyone which is probably why they diversify into other stuff like comics...etc.

Only times I ever pre-ordered anything was when they had awesome bonuses for free, i.e. my Bounty Hunters shirt for pre-ordering Metroid Prime 2. Doesn't happen too often though.

I preorder to lock in sales & get bonus offers.  That's the only reason I'll preorder.

" I preorder to lock in sales & get bonus offers.  That's the only reason I'll preorder. "

For the business side, it's basically a guarantee that you have a unit being sold at launch.  Unfortunately,  there seems to a move towards instant sales in our industry, much aligning with the Box Office for the film industry.   
 
For the consumer, often times the market is far tougher than what you have described.  The publisher or developer will often throw in some type of incentive for pre-ordering.  Be it a soundtrack, poster, golden guns, etc.  It also is supposed to guarantee a copy for the consumer for up to 48 hours after the release of the game.

I do it sometimes if I want to trade in a game towards something in the future before the price on the trade in goes down. Its also good for paying for games in stages. Like $10 a month or something.