The wings carry fuel and they're made of carbon fiber and aluminum, lightweight materials. They have to be light relative to the overall mass of the plane to minimize wing loading.

The fuselage contains landing gear, bulkheads, cargo, fuel, APU, and so on, which are not lightweight and not made of cardboard (WTF?) and the body is oriented longitudinally so it drives all that mass into a smaller cross section, whereas the wings distribute their impact over a wider area.

Also, there were conspicuous scorch marks on the wall in the shape of the wings, with a bigger, deeper mark where the engines were, which you'd expect if the fuel in the wings exploded and the entire wing assemblies disintegrated. Also, it doesn't really make sense that the Pentagon would attack itself with a missile. If they want to assassinate people they'll just kill them through covert means. If they need to destroy evidence they'll burn it.

The more incredible story is the missile one, you have to suspend critical thinking and ignore important facts to believe it.