I like the idea of separation of services. ISPs provide a pipe. Other vendors provide security. Other vendors provide email. When one party controls all the services, it's a 'synergy' for the company, but rarely for the consumer.
With DNS, it's possible to control key components of Internet navigation. Google already controls search, they are quickly gaining market share to control the browser, and when you put in DNS, it becomes the trifecta of complete navigational control.