Another way to look at the attack in Paris is perhaps we have hurt them so badly that they feel a need to lash out.
They say that a wounded and cornered animal is the most dangerous. Perhaps Daesh has been hit hard by the combined forces arrayed against them that they have reached out to try and change the tide by increasing paranoia in Europe so that more Muslim reinforcements join their cause.
Bloomberg has a good article on the difficulties of destroying Daesh:
http://www.bloomberg.com/news/articl...uge-challenges