This kind of stuff is way worse to me than murder. These ancient sites are all of our histories, they tell the stories of how human civilizations rose and fell. Once gone, the secrets they held can never be reclaimed. A complete shame and crime against humanity. I wish they would stick to cutting people's heads off, we have enough people to spare.
In a way, I share this sentiment. These groups aim at destroying history, for people without history and without past are so much easier to subjugate. But at the same time in this destruction, they write the history of their own demise and their own savageness, for that is how they will be remembered - as illiterate savages.
It's like Taliban and their destruction of the statues of Buddha all over again, this time on a larger scale.
