I'm always hearing about how the airline industry (including the career paths of airline pilots) have changed since 9/11 but no exact details on WHAT or HOW things changed. If its that less people are flying, isn't that no longer the case since we are talking about exponential increases in air travel over the next 10 years?

So, at the risk of sounding naive, could someone shed some light on what exactly changed?

I was only a kid when 9/11 happened so I really haven't followed the changes as they happened.