[eno_]

if it's not financially feasible those towers won't be rebuilt

That should be the only criterion.

[robertpaulsen]

Keep in mind that there's more than one way to make the towers financially feasible.

Yes, it may be difficult to lease the upper floors. Fine. Leave them empty and finance the added construction cost with donations or a federal handout.

Personally, I would pay to see the towers back and two stories higher. Every time I see an old movie located in New York and the camera shows the towers, it strengthens my resolve to rebuild.