I don't think they want that. They take this course because "this was preventable!" is very politically disruptive. None of them want to be the guy who voted against mandatory data retention only to play host to an attack on home soil months later. It's sad, but that's the reality.
The history of government spying, at least as far back as J Edgar Hoover, as been about spying on members of the opposition, not about ass-covering. ass-covering is just the current halfway-excuse.
Imagine being in a political party while private intelligence contractor give you access to all the emails from the other side. You can know where all the activists are at any moment, and what the internal conflicts are, and what areas is focused. What would be your reaction if phones suddenly started to get encrypted?