Because, Mr President, it is not enough to be "supportive" of ending "Don't Ask, Don't Tell." When you have the presidency and your party controls both Houses of Congress, it's a matter of having the political will to end it. Not all gay people are HRC-fundraisers. Some are even risking their lives every day for this country, in uniform, only to be treated like second class human beings and citizens by their own government.
Their own government? That means you, Mr President and Senator Boxer.