Not at all, what makes you think that?
Because why would you give in to the terrorist's intentions and abandon a part of what makes NY what it is? I work across the street from ground zero. The only people who visit it now are yokel tourists, and if it becomes exclusively a memorial, the only people who will visit it then will be the same hayseeds.
If we really wanted to honor the dad, we'd build it back the way it was, only taller. And the Cross and the twisted facade would be in the courtyard. All of the people who died have graves in peaceful cemetaries. The actual site should be an in-your-face reminder of what happened, because more than half of the country seems to have forgotten already.