Comcast didn’t invent the Internet. Indeed, it, and most other cable companies, were relatively slow to recognize the important value the Internet would provide both to the public and to companies providing Internet service.[...]But if Comcast is to benefit from the Internet, it is perfectly reasonable that it be required to do so in a manner that doesn’t pollute the value of the Internet for everyone else. Yet that is what Comcast has done here. By secretly adding a layer of secret sauce into the Internet that interferes with legitimate applications and network services, Comcast has injured the value of the Internet to other innovators. By denying that it has done this, it has added insult to that injury. The Commission has done us all a great service by stating clearly that it will assure that the platform for innovation that the Internet is will not be compromised by such behavior.

It is worth reading the whole Lessig letter as he explains the principles and architecture of the open Internet quite clearly.