Because it would very likely tip over, or at least veer to one direction, instead of folding neatly into itself.
Did all the people in the building not see the dynamite strapped to the pillars?
What makes you assume dynamite?
Did they not see the 100s of meters of wires?
What makes you assume wires?
When did the guys that wired the build do the wiring?
Who knows? When did the dude who sucked at flying sports planes learn to fly a boeing so well? How did a passport of one of the attackers allegedly get found on the scene? If you want a conspiracy theory, try a bunch of guys taking down THREE high rises with TWO airplanes and a bunch of box cutters. Hah.
Was it during working hours or after hours?
How is that relevant?
How come no camera, person or security guard managed to see them?
Are you say it's not possible to deposit bags of C4 (etc.) with remote triggers in the right spots even just 10 minutes before impact, and safely get out? Or, to be alone in a room just enough to hide it in the ceiling or walls or wherever? I'm not saying it's easy, but it seems easier than even just flying a boeing so well without practical experience, or such a tall skyscraper folding neatly just by pure luck, and both of that happening twice on one day.