HalloweenWeed makes an excellent point, that if the media and others ignored acts of terrorism they would fail. By their very nature they need publicity to fuel the fires.
Like an unruly toddler if you play into their tantrums they feed of it, ignore them and tantrum stops.
Trouble is there is a lot of money in news!
One day Alice came to a fork in the road and saw a Cheshire cat in a tree. "Which road do I take?" she asked. "Where do you want to go?" was his response. "I don't know", Alice answered. "Then", said the cat, "It doesn't matter.”