Why not ruin a ruin? For the iconoclastic torturers and killers of ISIS, the ruins of Palmyra were a blight that must be eradicated. Any achievement of man, that is not a product of Islam, is thought of as an evil influence.
Of the 500 top universities in the world , not one is born of an Islamic country. Islam identifies knowledge as evil. Mindless obedience to the point of death is considered holy. Kalhed al-Assad the 82-year-old professor and custodian of the antiquities, refused to give up the location of ancient artifacts. He was tortured and then killed. His body hung on public display. Isis killed in order to destroy,= villains. Kalhed died to preserve part of our heritage.= A hero.