Let's not forget that there was heightened general concern about terrorist activity even before 9/11. For the Atlanta Olympics in 1996, for example, there was quite a bit of security at the venues and the big fear of every Olympics not to have a repeat of Munich 1972. What they got was a Boston-like bombing by a homegrown right-wing terrorist in a park with less security but still associated with the Olympics.
New year 2000 was tamped down a lot in most places, and even in places celebrating like Times Square they took extra measures, sealed the manholes, etc.
With the private sector running security and it going to the lowest bidder, though, even those concerns don't translate to better procedures. For all the game they talk, airlines hate to spend their OWN money on security and will run to the government for everything from TSA to getting funding for the new cockpit doors. That angle was underreported but is as true today as it was then.
Airport security was really bad before 9/11, and in ATL you had a revolving door of $6-an-hour people treating it like a dead-end job. They needed to professionalize the force, and of course the screenings would be much more thorough. I think the people throwing spitballs at TSA are just counting on reaching a point when most flyers won't be able to remember what it used to be like.
As for the OP's question, I'd also point out that airlines had gotten stricter about things like IDs before 9/11 for their own selfish purposes. It used to be about 30 or so years ago that tickets were sold via classifieds with about the only qualifier (besides destination and dates, natch) being male/female, as the airlines didn't check ID domestically.
It also used to be that you could get boarding passes printed up in advance, sometimes making throwaway ticketing possible (but you'd NEED that and other tricks in places because fortress hubs were stronger and LCCs just getting started). That was do-able up until the mid-1990s.
And does anyone remember the fight over templates and UA trying to make airport security the enforcers of carry-on baggage rules? That kind of cynical thing also went on.
Overall we were headed to more security, though it took 9/11 to get a TSA, DHS and some of the rules like the one about liquids. OTOH, in absence of 9/11 an attack like the shoe bomber or underwear bomber, if successful, would also have had a lot of impact.