No one here seriously has a problem with law enforcement monitoring legitimate suspects for potential risk. We *DO* have a serious problem with wholesale monitoring of personal communications, absent probable cause, in the hope of catching someone, somewhere, doing something they don't like. The notion of 'general warrants' by the British authorities was the reason for their explicit ban in the Fourth Amendment. And the whole 'Founders didn't have to deal with terrorists' argument is put to bed by a quote from Madison to Jefferson: "It is a universal truth that the loss of liberty at home is to be charged to the provisions against danger, real or pretended, from abroad."
The majority of the disrupted terror plots since 9/11 have been accomplished by old-school boots-on-ground detective work, not by signals intelligence. There is no indication that plotters like the Boston Marathon bombers, etc, that *were* sadly successful had used any crypto in their communications. The 'lone wolf' nutcase is by nature hard to track. Most of the additional screening put in place since the attacks has been window dressing ("security theater") meant to make us feel safer, not particularly contributing to actual security.
The solution to terrorism is NOT TO BE TERRORIZED, to deal with the nutjobs as just that, and refuse to turn ourselves into the sort of regulated police state they'd prefer to see.