This makes a little more sense; gutting it for profit rather
  than blowing it up. They need to get money somehow and seizing
  ruins for-profit makes sense.

  Then again, there might have been no street-value on what was
  left over and then they blew that up. That's possible. But
  considering the photos were distributed by ISIS themselves, my
  gut tells me they're hiding something; *appearing* merciless is
  a VERY important image for them to project in this 21st century
  media war, and they know how to play the game very well.