The reality is, of course, encryption was used in these attacks. These terrorists aren't stupid. That doesn't mean it needs to be banned the say way a randoms stabbing don't mean knives need to be banned. I think the people saying "No way, never no encryption has every been used for nefarious purposes" are just as bad as the other side. Having a sophisticated view of this stuff makes a lot more sense.
Encryption will be like the gun debate. It will flare up from time to time. Its an easy horse to beat because its too technical for the layperson to really have a good understanding of and clearly there are political elements that would love Clinton-era laws limiting key size and such. The reality is that this ship has long sailed away. The genie is long out of the bottle to control encryption like its 1993.