As a European, I'm fascinated by this train of conversation.
In no way are Americans wimps. Witness the 200k troops currently in the Middle East. However, there are obviously issues surrounding willingness to fly.
My big concern is that as people decide not to fly....airlines go out of business..and when they decide that they DO want to fly, prices are increased and destinations are reduced, making the practicality of travel a self-fulfiling prophesy.
IMHO the decision not to fly at the moment is not bourne out of rational judgement. I can understand it, but only on an emothional level.
Obviously 9/11 has shown us that bad things happen to innocent people on regular flights and on the ground.
However, looking at pure statistics, the chances of a similar thing happening again are tiny. Do the people who are not flying, also avoid going into high-rise buildings?
I believe that the world is not even "less safe" than it was before....it is just that we are more aware of the threats to us.
There are two sorts of life that people can lead:
1) Avoid all risks
2) Cautious - be aware that risks are everywhere, but lead life as you want to live it.
I ride a motorcycle - something that is more likely to lead to my demise than anything else that I do. However, the pleasure that it brings me, outweighs the danger that I know it brings to me.
Travel is exactly the same. Evaluate it rationally together with the pleasure or fulfilment that it brings to you.

The ability to travel the world cheaply and easily is a real gift to our generation. In the next 2 months, I will be traveling to Russia, Vegas and France (on holiday), and possibly Japan (on business). There is no way that I would let the current world order interfere with my plans.