The feds can look at or listen to anything of mine they care to, I'm no threat to our nations security or anything else I should not be. BUT they aren't trying to invade anyone's privacy or otherwise cross lines of decency.
They're looking for patterns of communication between suspicious parties that might indicate plans for another 9/11...parties usually afforded the same right to privacy (secrecy?) the rest of us, ordinary loyal citizens, enjoy as provided by our free society through our constitution.
These 'suspect parties' might be ordinary enough themselves, like simple immigrants from repressive foreign soils hoping for a chance to enjoy the style of living we've complacently come to take for granted... but they may also be elements of another wave of interlopers planning to strike at our nation and take more innocent lives in their quest for Islamic sainthood, or whatever the Hell they think such atrocities will achieve!
Some of those 'patterns of communication' could involve foreign embassies of less than friendly regimes as well, overtly or under the guise of some "sheep-suited" decoy entity. In the event another plot was hatched or discovered early and pre-empted, the 'Smoking Gun' would be found, evidence of deliberate hostile intention by the foreign power in question... hard undeniable evidence of malice.
I personally have no doubt that such nationalized malice DOES exist, and concrete proof would be very helpful in justifying any retribution our government would exact upon such a rogue state in the global arena.
So, look in my windows all you want... if it helps uncover or prevent EVEN ONE conspiratory endeavor, it's entirely worth it. :-)
ADDENDUM:
There does exist ONE concern in terms of loss of privacy, etc. due to the "Big Brother is Watching" issue... if a repressive regime takes power after the next elections (Hillary, et al) the internal spy network in place would almost certainly be employed by the powers-that-be to abuse ordinary citizens, directly or as justification for further legislation repressing the rights of US citizens via sensationalistic presentation of the issues involved, like the 'assault weapons ban' a few years ago. :x