Ultimately, Dave wants to make it easy for anyone to write the Web. Radio is a personal Web application server. It comes with a nice app that gets news via RSS and publishes a blog and RSS channels as output. But the app is just there as a bootstrap, to give developers ideas, and to give users a way to get started. To interest the developers, there have to be users.
Content management is a basic building block.
I'd like to say that we all got together for Thai food and dreamed it up and knew what it would look like and how it would work five years ago, but that would not be true. It's an iterative software design process. Take a step, learn from it, use the experience to guide you to the next step. Since 1996 when we switched to Internet development, the goal has been to create a fantastic multi-user writing environment built around the Web. Radio is an important step for us in this process because we've taken what we know about the Web, HTML, browsers and servers, and redistributed the code so more of the work is being done on the user's workstation.