When was the last plane "bombing" before 9/11? I'm sure you would have told the people on that flight the same thing.
I think it is wrong, but I mean I think airports should check them more often then other people, but not take extra time doing it or more technology to do so.
Also, to whoever said the ratio of bad arabs to good arabs is low, there is still a ratio. When was the last time the US terrorized another nation for no reason? The war right now is a response, Hiroshima and Nagasaki were a response, D-Day was a response. When was the last time you saw something on TV about US citizens (not even government) committing acts of terrorism in another nation?
It is part of their religion. Well that is an overstatement since some take it to extreme levels and interpret it differently, but a percentage of their population could believe that terrorism is for the better, so I think it is necessary just to be a little discriminate in airports and international boundaries and such. It's just another precaution to protect the US. I do not think they need to use extra resources, time, or money when "checking" them.
As for wire tapping people who are already here, that is wrong. That's being paranoid and violating US privacy laws.