They wrote a 600 page report about it and it included a ton of recommendations. Not many people remember at this point, but for months and even a few years after, the entire country was on edge about it happening again, in different means (trains, car wrecks on purpose, shootings). There is a reason they have called this a post-911 world ever since. That hasn't ended.

You forgot the paranoia after it. Along with surrendering anything in the name of anti-terrorist measures. And protecting children.