In order to convince more gamers to pre-order their games ahead of time, retailers such as Gamestop began offering pre-order incentives, and the practice has continued to be implemented to this day. These incentives tend to be things like extra missions, weapons, or costumes. While there are some perks to offering such content, this practice is annoying because of the way it segregates content between gamers.
Mortal Kombat 2011 is a great example of this. Depending on what retailer you preorder it at, youd get an extra costume and fatality for a certain character. Those who preordered at Gamestop got the original Scorpion costume and fatality, while those who preordered at Best Buy got the original Sub-Zero costume and fatality. And those who preordered at Amazon got the original Reptile costume and fatality. There were more, but I cant be bothered to remember. There was so much preorder content that people actually started auctioning them off on Ebay to those fans who wanted them all.
I, and many others, complain about this practice because certain gamers are being denied content based on who they purchase the game from. It makes the simple act of buying a video game a game itself where you have to actually give thought to who you want to give your money to. It may be a somewhat trivial thing to complain about, but it is without a doubt an annoyance.