I don’t care what side your politics are. When corporations can so easily control the voice of the elected leader of a country (one who has genuine legitimate support or about half of the country), I become very scared for the future. Corporations should not have more power than the elected officials.
There is nothing to prevent any politician from doing what was done before Twitter/FB - holding a press conference and inviting the press/TV. Or putting out public statements which are widely disseminated over news/pr wires.
I'm a little surprised a blog hasn't already sprung up on whitehouse.gov.