It's about choosing what parts of our history we celebrate. To honor racists who became traitors to the United States to try and keep black people enslaved is disgusting.
We should not honor them. They represent the worst of us. Take them down and replace them with iconic Black Americans who have always been the ones to force this country to live up to their stated ideals.
These monuments are the visual representation of the fact the Confederacy never truly died. It was kept alive via botched Reconstruction, Jim Crow laws, etc. Let's tear them down and finally reconstruct.