The title: Barack Obama is Bi-racial: NOT JUST THE BLACK GUY," tells the whole story of why Barack Obama doesn't describe himself as bi-racial. If, because he's "black," all of his accomplishments are reduced to "just the black guy?" But if he's bi-racial, purportedly he can be credited with what he's achieved. That's just another level of racism. But, for as much as some bi-racial wish that were true, if they were paying attention, they would notice that the racist establishment is trying to prevent Obama from achieving, while denying what he's achieved. So, even while they know he's bi-racial, that doesn't stop them from trying to do to him what the title suggests should happen if you are a person of African descent who is not bi-racial, namely, no matter what you achieve, socially you are reduced to "just that black guy."
There are plenty of white people who have people of color in their blood line, and if you as, they will tell you, but they don't call themselves bi-racial, they don't because they aren't afraid of being identified as what they look like, namely, white. Most bi-racial people want to present their racial non-pedigree because they are hopeful that it will exempt them from the devaluation that is applied to people who are of African descent. But they can't seem to get it through their heads that no matter how you describe yourself, people are going to react to your appearance, and they are going to treat you consistent with what that means to them. And when you try to distinguish yourself racially, you put yourself at risk for what they have to say about it, like the guy on a talk show who said he was by-racial, and another guest made it a point to thereafter call him black, or like Halley Barry, who was told by a white classmate, "that white woman is not your mother ..."
Barack Obama is too smart to play that loosing race game. Consider this, there is no person of African descent, who advocated for acknowledgement of their racial distinction from others who are of African descent, who amounted to anything.