If you're discussing how to bomb your local city and sending recipes for IED's across your e-mail, then you're in trouble.
I don't do that, so I don't give a stuff if someone can read my stuff.
They could easily do so in any number of ways.
I've got nothing to be guilty about, so I don't care.
And I'm not going to be sending majorly private and confidential stuff over something as unsecure as e-mail or Facebook or Skype anyway.
And if it catches terrorists and murderers, like those behind the Boston Marathon or the Woolwich murders, I am exceedingly happy the scheme is there.