Apple's got you covered. According to their Plan For World Domination you are supposed to replace your Apple hardware every time a they come up with a new product or model.
Security through consumerism. Then you have to buy new connectors and cases and a new desk or outfit to go with your new shiny. Thus, it helps with the local and global economy and even generates more traffic on the Internet (all of those rantings on various support boards and all of those lovely adverts). Given Apple's push towards recyclable packaging products, it helps those companies as well.
What's not to like?