I don't understand what is complicated about this, or what even lends itself to a plausible need for a conspiracy.
Uncontrolled fire. It burned, then it fell. Period.
So what?
http://rememberbuilding7.org/7-facts-about-building-7/
I don't know why people don't accepting facts, what happened and what is behind all of this and if we don't talk about insurance we can't get big picture.
It is a fact that it was more or less the first fire induced collapse of a steel frame high rise. So what? It was designed with the assumption that the sprinkler system and the water would be working to prevent fires and their effects.
Take those away, and you have the situation which existed. There is no need to invoke conspiracies.