Normally I would agree with you. But I think it is imperative that the Center be rebuilt, and exactly where it once stood.
Memorials are all very fine. We've got the Arizona Memorial in Pearl Harbor. And I would favor something similar to it in WTC Plaza.
But to leave a gaping hole in the ground -- a smoldering ruin -- as a shrine to the dead would be equivalent to leaving the destroyed and sunken battleships in Pearl Harbor as a monument to the casualties there.
The Center must be rebuilt, because a renewed WTC would be a definitive statement of resurgence. And that would be the best memorial to the dead I can think of.
Interesting dichotomy of opinion on this thread. But I think you're sentiment is correct. It is not a dishonor to those who died on this land to rebuild a useful and inspiring structure on it. When faced with this kind of adversity, a new structure would symbolize defiance and courage, not humiliation and acceptance.
Would a new WTC become just another terrorist target? Probably. But, then again, there is no lack of targets in this country. Apparently further hijacking attempts were foiled yesterday. Where were they going? They have already taken out the WTC, but were still going after something. If we let our fear of attack become the driving force in our decisions are to whether or not to rebuild assets, we won't have much infrastructure left after numerous successful attacks. All the more reason to go after those responsible for these strikes and eradicate them.
If we are viewing this as a war, which many are doing, then we need to take a chapter from the wartime playbook. When you lose assets in a battle, you try as best you can to replace them. You don't throw in the towel after your opponent gives you a bloody nose. Rebuilding structures will not replace the dead and we should not forget them and their sacrifice, so some kind of memorial is appropriate. But a rebuilt and better WTC would serve both that end and inspire those left behind to endure and continue the fight.