didn't they catch the Boston bombers? Or at least have some fucking clue what those two were up to?
This is an incredible amount of information and government does not yet have the capability to sift through it looking to stop crime or terrorism. I'm not even sure that Google, Amazon or WalMart could handle this much data effectively. However, once there is a lead this information can be back-mined to discover links and gather proof. Thus although government could not stop the Boston bombers, they did identify and catch them incredibly quickly.
There was a program (probably still extant) in the 90s which copied all broadcast phone calls to the UK to be parsed. A program looked for key words and patterns, and flagged phone numbers. For positive hits, a more powerful, more sophisticated program scanned the calls, and in turn its positive hits were fed to an even more powerful, more sophisticated program. Obviously this takes a buttload of bandwidth and computer power. Eventually a human listened to the call. However, most CIA analysts did not (and probably still do not) actually fluently speak the languages of the nations or areas to which they are assigned, so generally this was handled by contract labor, usually immigrants from the regions themselves because of colloquialisms. The whole process was terribly time-consuming and expensive, and simple codes or even just some caution could defeat the system.
I do not believe that Obama would knowingly allow a terrorist attack to take place, and I'm sure that if he did there are men and women who would stop him out of patriotism or compassion or even simply party ideology. Government is composed of many different people, most of whom are perfectly decent people.