What is the basis for this comment, besides you personally wanting more black characters on the show?
Have you not noticed that none of the extras are black either? It is because there aren't that many black people in San Francisco.
In reality, it has exactly enough black people(1-debatably). If this show was happening in D.C., Atlanta, New Orleans, or New York there would be a lot more, and it would be an entirely different show...but this ain't that.
If anything there should be more Asians and more Hispanics.
Why can't you value the show for what it is showing? GAY characters (plural) on mainstream TV in leading roles with situational (as opposed to slapstick Will & Grace sitcom) humor. I am sure HIV and other issues will come later on if it gets support, but those type of story lines need to be developed or else they lose their potential. I get your frustration about being underrepresented but to put more black people for the sake of black people being in the show wouldn't be representative of this microcosm of America.