Far as intelligence agencies, they've not just failed: they've often tried to cover it up, mislead other authorities, or even destroy evidence. The result of incompetent organizations not capitalizing on what they have even when it's obvious should be a net reduction of power and increase of accountability. Instead, they always ask for and often get the opposite.
The technically literate of us following the details should just keep reiterating to anyone that will listen the key detail: almost everyone whose launched an attack did it while already being under surveillance. It doesn't work. End of story.
Note: If it did, they just go back to doing what pro's already are in using human go-betweens and other low-to-no-tech methods like Osama did for years to dodge NSA. They didn't get him until someone tipped them off for the bounty per Hersh.