As to your comment about nothing changing in the last 15 years, do you mean terrorists trying to attack the US?
No, of course not - that sort of attack* is not preventable. No amount of infringement on freedoms can stop that. The FBI was informed that there were Saudi men taking flying lessons ($$$) who were completely unconcerned about landing or take-off, and the issue was buried within the FBI. The amount of intelligence is not the issue, it's the Feds' general incompetence that is (and always will be).
In fact, information theorists strongly warn that all of this extra "intelligence" makes things worse because it raises the noise floor significantly.
The NSA didn't stop the Boston bombings, and in Congressional testimony the NSA chief would admit that there were fewer than four potential events over a decade upon which all of their programs had any involvement in detecting, and in none of which was the NSA's intel required.
* asymmetrical, not 'airplanes as missiles' which hasn't been a viable strategy since 2004 when the last cockpit doors became hardened - the TSA is behavioral conditioning, not security.