While I agree that weakened steel (as opposed to melted) can collapse and the buildings could pancake, still there are two main things that bother me about this catastrophe.
1) Why would normal collapsing be virtually free-fall (i.e virtually frictionless fall)? While I think it is possible to fall, why not more slowly than it did? And a corollary to that, why straight down as opposed to part of the building not as hot or compromised than other parts causing the debris to fall to one side?
2) What about WTC7 which was not hit by a plane, and yet fire debris from the others just made it fall "straight down" in a "free-fall fashion" like the others? So that's 3 buildings that fell "straight down" in a "free-fall" in one day supposedly from hot fires when in all the history of sky-scraper fires there hasn't been one case like that in all the world. Hmmmmm.
But as Linus of the Peanuts comic strips once said, there's 3 things you don't talk about:
1) Religion
2) Politics and
3) The Great Pumpkin.
I'm going to add a forth, the WTC complex. People get way too emotional about it. So I won't say anything past my observations cited above.