"without taking a direct hit from a plane or having any major fires"
Ummm you might want to check your facts again. There was a major fire in the building and did you forget the thousands of pounds of debris that fell on to Blg. 7?
Firemen gave testimony that loud pops and creaks were being heard from the building and the order was given to pull back because of eminent collapse.
According to the project manager, Mr. DeMartini all those buildings were designed to withstand major impacts.....including jetliners and I'm sure falling debris.