Because with a population of 80,000,000 people, it is a great chance to promote the game to many different people who normally wouldn't watch hockey. This is great for hockey in general. Germany has the potential to be a hockey power because of their population and location. The IIHF is in charge of promoting hockey to the world, so why wouldn't they take advantage of this opportunity? Why have the WC in a country like Finland for example, when you could bring it to a relatively untapped market that has over 80 million people?