Bill Monroe, who was moderator for NBC's Meet the Press for about 10 years, is a longtime advocate of extending the First Amendment to broadcasting. Actually, I'm sure he thought that the First Amendment did cover all forms of the news media — but he knew that Congress and the courts didn't see it that way, so he wanted an explicit amendment to make that clear.
Because his articles on this topic were published in the pre-Internet Dark Ages (yes, children, there are great ideas not online), I can't link to any of them. But he briefly reprised the argument in the letters column of the Washington Post today, concluding:
Broadcasters are also open to government pressure through the Federal Communications Commission, whose members are appointed by the president. Newspapers are specifically protected against government interference by the granite wall known as the First Amendment.
When the present form of broadcast regulation was set up early in the previous century, nobody understood what powerful instruments of news and information would evolve from the primitive radio stations of that day. Now that we do understand it, we can repair that historic mistake. We can extend the clear, stirring language of the First Amendment to equal protection for freedom of the electronic media. The problem of allocating broadcast licenses does not have to cost the American people the benefit of free broadcasting.