The typical floor structural configuration for the World Trade Center Towers spanned from the exterior wall columns to where the inner 49 columns formed support for the elevator shafts, stair towers, air shafts and mechanical systems. Thus, each floor was NOT a monolithic slab and structural system spanning across each tower from one exterior wall to the other three, as we are led to believe. Each floor, in fact, terminating at the contiguous structural core, resembled a square 'donut', with the structural core, so to speak, being the 'donut' hole. Failure of floor structural support in any quadrant of the building plan, or even in any half, thus, would have failed ASSYMETRICALLY.
In other words, an initiating collapse would have only been to one section of the floor, hinged at the core and pulling free at one of the walls. The entire floor would not have collapsed unless the core was cut. Hence, "Pancaking" is impossible.