Hmmm. From a terrorist's point of view, those who bypass encryption entirely will survive, at least for long enough to do what they intend. A one-to-one conversation on a beach or other exposed place is a good way of achieving this, and it would appear that they know it.
Those IS nutjobs seem to have learned that the best way to avoid being trapped in the mesh of surveillance programs is to fragment their operations to the extent that they all operate as lone wolves. It clearly works.
Most people who need to be concerned about excessive and intrusive government surveillance are everyday people who just like to have the bathroom door shut while they're having a dump.