What's more important than changing the behavior of "Joe User" is changing the behavior of "Joe IT", who makes the tools "Joe User" uses. Adding end-to-end encryption to highly popular services, making it very easy to use, or even making it all work in the background without "Joe User" even knowing about it, is much more effective and faster than teaching every single Joe Use to use end-to-end encryption.

Imagine if Hangouts and Whatsapp added end-to-end encryption to their services, the way TextSecure works. BOOM - 1 billion people now using end to end encryption, most without even realizing it. That's as "world changing" as it can get, and hopefully, something like this will eventually happen on popular platforms.

Changing the behavior of "Joe Tech Evangelist" is also extremely important. "Joe Tech Evangelist" is basically what caused Chrome to go from 0 percent market share to 50 percent market share (in some stats). Google's advertising of Chrome didn't do nearly as much as every tech guy out there pushing Chrome onto their families and friends, who were still using IE, and some even Firefox.

And if "Joe IT" doesn't make the kind of services that offer really strong encryption and security, he should be very worried "Joe Tech Evangelist" will push users towards the platforms that have it anyway, and (eventually) lose its userbase. But it obviously won't happen overnight, and it also depends on the commitment of "Joe Tech Evangelist" to do this.

It propably at least changed the search behavior of the Bad Guys.

Stupid bad guys. Smart ones already assumed the NSA was poring through everything.

Take a look at the average violent criminal. The stupid ones are just as dangerous as the smart ones, and there's a lot more of them.

Terrorists aren't much like criminals. For a start, they're ideologically motivated. And that's the argument for why we as a society, need to treat terrorists differently than criminals in the first place.

There's only a very, very few terrorists, even when the US government has done its level best to create as many as possible. I doubt we can take a quantitative argument like yours and get decent results.

The term "bad guys" is much broader than just terrorist. Feel free to substitute "drug smugglers", "human traffickers", "members of organized crime groups", "militant extremists", or, yes, even "terrorists". Nor did I make any argument as to how to handle any of them. The point is that you don't have to be smart to cause harm. The smart ones were presumably harder to track beforehand; the not-so-smart ones are likely a lot smarter now.

Of course. As well as there will still be some that are even more stupid so we can have nice statistics about how successful the new tools are.