I think that the guy who had purchased the buildings before 9/11 learned that renovating any part of the building was extremely expensive because new building codes required the complete removal of the spray on abstestos fire proofing of the interior walls which is an extremely arduous and dangerous task on its own. He got a very handsome insurance payout after the buildings collapsed.

This, coupled with Building 7 also somehow being demolished at the same time despite not even being hit by a plane, and people on the ground such as cops and fire fighters being told that Building 7 was going to be "brought down" despite only suffering fire damage, which has never caused a high rise to collapse before or after 9/11. This has basically convinced me that these properties were chosen on purpose, and they weren't just targets that the terrorists picked completely of their own volition.

Edit: I forgot to mention that NORAD was also rescheduled to start running a shitload of commercial airplane hijacking simulations the day it happened, and those simulations continued running for a while AFTER the hijackings occurred, thoroughly confusing the absolute shit out of people trying to organize interceptors, most of which didn't even have the fuel or ammo to respond because they've been running simulations all day