I also liked the film, but thought Morgan Freeman's argument -- in the very first minutes, in fact -- wasn't sufficiently acknowledged, developed or discussed.
One argument for ending the event that I didn't hear in the film is that Black History Month may be counterproductive. Other groups silently question the need for this event and resent what they feel is merely another example of affirmative action or black victimhood. Other Americans look at the black heroes (King, Tubman, Parks and Douglas) and say, "That's all you got? What about my heroes? What about the melting pot? Why are we trying to Balkanize ourselves?"
At almost 70 and a wide reader of history, I've come to approach some understanding of how interwoven blacks are in American history (and how separate). Declaring a month for black history is, as the narrator said, to minimize black contributions to America (music, sports, arts, among others), to imply that blacks are different enough to not even be American.
One of the most profound observations in the film was made by a young teenage girl in braces sitting in her bedroom.
At one time, we learn in the film, America had Black History Week. Today, as segregation and inequality are legally (and, as I see it, effectively) banished, I propose it should be Black History Day. A day for all Americans to reflect on the great black figures in history, to honor their lives. And then, for some of us who merely have a darker skin, to go on being not African-Americans, but Americans.