I do wonder just how good most encryption is, anyway. And even then, they'll probably have a clause that means, when asked, you have to be able to unencrypt everything for them to look at. Not sure if that's possible with point-to-point encryption, though.
Presumably the reason they want to do this, ostensibly, is for our nation's safety: to cotton on to 'terrorist threats' (fuzzy terminology for the win) before they (the terrorists... no, not the government, the other terrorists) get a chance to carry out their plans.
In practice, we lost the war on terrorism the day we installed the first full-body X-ray scanner in our airports. Anything further that our government imposes on us now is just adding insult to injury.
If anyone hasn't bought tickets to see Yes Prime Minister on stage near them while this tour is ongoing, I can thoroughly recommend it.