Debatable if the Arab Spring would have occurred without it, as the Middle East might have been much more stable.
Would Brexit have happened without 9/11?
There's an ancient TIME article I have in my archives highlighting how the Dubya admin ignored Clinton's intelligence team's attempts to hand over info about the threat of a terrorist attack in the US. Would 9/11 have been prevented if Gore had won 2000? God damn hanging chads and rigged elections...
It doesn't go anywhere because there is now a lot of private industry in it for contract money to supply the spectacle whom have the lobbying power to keep it in place, but it is a total waste of money and gross violation of privacy for no positive benefit to society.
[1] https://www.huffpost.com/entry/tsa-fails-95-percent-tests-ho...
In particular you'll see other countries focus on measures like interviewing (briefly) the passengers as they board.