You have to look at it from the employees point of view. As an ex gamestop employee I can tell you are not the first customer to come in that store and ask for free stuff. Infact you are porbably the 50th person that day that has asked for stuff and gives nothing in return. As stated earlier the purpose of the free promotional stuff is to guarantee sales for that store by offering the items to people that preorder games.
Also if you are infact 16, I say you get a job at a local gamestore so you can not only make money, but also take home a bunch of cool collectibles in the process without having to preorder anything