I agree with zuglo - a societal consensus - in a democracy - is reached as to what should be memorialized and what should not and happens on a specific basis. What is acceptable or not can shift over time as it has with the symbols of Confederacy. If American race relations are to be improved - and they desperately need to be - the place of these symbols, so offensive to a large part of the population in the South (and not just black Americans), have to be re-thought.  This also happens in the other direction, too, as forgotten or previously unrecognized individuals are lauded long after their deeds. 

As I said in a response to another poster below, this shift IS history and not a "rewriting" of it. History is not an immovable iceberg written only once.