Much smaller plane
The flight was near the end, so the fuel tank was near empty, and the pilot likely dumped the remaining fuel. There wasn't even a fire.
The plane fell on house due to engine stall, rather than flying straight into the building at full throttle.
This pilot was probably trying to avoid killing people in the crash, rather than doing the maximum possible damage.
A house is not the least bit reinforced against falling airplane damage. The Pentagon is protected by materials designed to absorb the impact of a bomb.
And most of all, what kind of 'missile' sets a huge fire but doesn't explode? If you're going to chase conspiracy theories, come up with one that makes sense.