Even The Term Was Run Past Focus Groups

Did 9/11 really "Change Everything"?

"We've been told that 9/11 changed everything.

Is it true?

Let's look:

•The Afghanistan war was planned before 9/11 (see this and this)
•The decision to launch the Iraq war was made before 9/11. Indeed, former CIA director George Tenet said that the White House wanted to invade Iraq long before 9/11, and inserted "crap" in its justifications for invading Iraq. Former Treasury Secretary Paul O'Neill - who sat on the National Security Council - also says that Bush planned the Iraq war before9/11. And top British officials say that the U.S. discussed Iraq regime change one month after Bush took office
•Cheney apparently even made Iraqi's oil fields a national security priority before 9/11
•The Patriot Act was planned before 9/11
•Cheney dreamed of giving the White House the powers of a monarch long before 9/11
•Cheney and Rumsfeld actively generated fake intelligence which exaggerated the threat from an enemy in order to justify huge amounts of military spending long before 9/11. And see this
•Cheney and the rest of the neocons lamented - before 9/11 - that America could not truly project its power globally without the justification of a "new Pearl Harbor"
•The government's spying on Americans began before 9/11 (confirmed here and here. And see this)
•The decision to threaten to bomb Iran was made before 9/11
•The government knew that terrorists could use planes as weapons -- and had even run its own drills of planes being used as weapons against the World Trade Center and other U.S. high-profile buildings, using REAL airplanes -- all before 9/11
•The government heard the 9/11 plans from the hijackers' own mouths before 9/11
•Cheney was in charge of all counter-terrorism programs for the United States before (and on) 9/11. See this Department of State announcement, this CNN article and this essay
•It was known long before 9/11 that torture doesn't work to produce accurate intelligence, but is an effective way to terrorize people

So did 9/11 really "change everything"? Or was it simply an excuse to implement existing plans?"

This is an excellent point. I got caught up in the manufactured shock and awe just like everybody else in the hours and days after they pulled their stunt off, although it didn't take long on Black Tuesday to figure out something was decidedly wrong with the narrative.
The fascist state was long in preparation just like how they slowly prepped the towers for demolition. But they needed the definitive event to put the pedal to the metal as justification for everything they had ready and waiting in the wings.
Hence just as all the actors in the Bush mob were singing in unison about how we'd go after the designated villains "wherever they were' along with "whoever harbored them" to justify Afghanistan, they stressed that the Big Lollapalooza was going to be the Big Excuse for transforming our reality into the current horror show. I remember it as a talking point for weeks afterwards.