I pre-order games because I think they will be excellent games and I support the producers, the development companies started accepting pre-orders so stores could order in enough product so that everybody can get a copy of the game now a days this is still true, but you get extremely cool content, the game will not be incomplete without the metal case or some different weapons, it's just an added bonus to pre-order, besides most of the pre-order bonuses are made available to everybody at a later date.