The problem is that techniques like this appear to be the only reasonable defense against abuse by the NSA. Collateral damage to more legitimate (limited, targeted, warranted) law enforcement is an unfortunate result, but fundamentally it's come about as a result of massive governmental overreach and abuse of trust.
If law enforcement agencies want the pendulum to swing back in the other direction, they should also be hoping for the overreach to end - not just blaming tech companies.
It's not a defense against the NSA at all. The iPhone encryption that's being debated only protects data physically residing on the phone itself. When was the last time the NSA had your phone in its possession?
Good point! I was speaking about more pervasive encryption in general, and it's fair to say I didn't consider the topic in question sufficiently before replying.
That said, It's worth pointing out that the NSA is known to have been active in exploiting endpoints, not just retrieving data from google/facebook/whatever. Of course it's questionable whether this would provide any substantial protection against such an exploitation.
If law enforcement agencies want the pendulum to swing back in the other direction, they should also be hoping for the overreach to end - not just blaming tech companies.