Because, in a futile attempt to pave over racial bigotry, the people who want these statues pulled down think that racism in America will magically disappear, once the statues are gone.  Poof, gone!  Just like that!  

The irony is that not only will racism NOT disappear, but removing the statues also fans the flames of aggression and anger, and emboldens the alt-right further, possibly pushing them  underground, out of sight from the public and the media, in order to devise new strategies to disrupt America, possibly even another Oklahoma bombing.  The alt-right is just another terrorist group, like the Taliban or ISIS, so why the left and the media think that allowing this group to become like ISIS, through heavy censorship, is totally beyond me.  Better to shine a light on this group, and let society decide for itself.  As for the statues, better to leave some in place, just some, but provide additional plaques or monuments to highlight how they sadly contributed to an unjust past.