Perhaps the outrage of some would be better directed at the Union Jack, for it was this flag which flew on many of the slave ships. These ships sailed for The New World after their captains has purchased human beings from the same African tribal leaders who willingly sold them. These human beings were captives who had been members of rival tribes.
The Stars and Bars is a part of our nation's history, as is the Union Jack and other symbols which help to tell the story of how America got to where it is today. The confederate flag flew for many years over Missouri's confederate cemetaries until quite recently when then Rep. Dick Gephardt pressured state and local officials to stop flying it.
The Left has a strange take on symbols. It works to keep the confederate flag from being flown over the most proper places to hoist it- when the confederate war dead are buried. Yet it has no problem with wearing Che Guevera t-shirts and flying of North Vietnamese flags. Go figure...