We all know that games are being developed for a certain concept that the creator thinks off. We all know that while the game is being developed a lot of things are popping up, which are the problems that the developers should fix for it to be perfect and for it to be realest.
There are games that are being play with the use of cd keys, for some reason. Like wrath of the lich kind cd key, this is a use for the game. I think that developer did those cd keys to earn money as the player buy wrath of the lich king cd key. And you are force to buy wrath of the lich king because it is a requirement for you.