My understanding is that this bulk data gathering is not as much as preventing attacks but further securing of power for the strange amalgamation that we would call the federal government.
I know in other fields the ability to do concept searching (via LSI and other techniques), rather than simple text based searching, has been in use for many years. His example/problem of a search for "bomb" bringing up noise (such as an email talking about a QB throwing a 'bomb' pass) should have long ago been solved.
Neural networks, with enough training data (which the NSA surely possesses), and enough compute power (which the NSA also possesses), could easily do this.
Note that one of the more useful and interesting uses for this data would be political demographic analysis more comprehensive than anything available legitimately. It could also be used to target leakers, especially if you could use devices to put 3rd parties in the same room. E.g. my phone hears or sees you and your friend together, even if you don't have phones.
The bar for collusion is really low. Look at what happened to the pot dealer for the guys that bombed the Boston marathon.
The odds of any one transaction coming back to get you are practically and almost literally zero but when something bad happens it doesn't happen in a vacuum. The bank robbers have to buy their getaway car from someone.