The story is that the French built these hardened aircraft shelters in the early eighties, and there is now a lawsuit between the Kuwaiti government and the French construction people over filling the walls and ceiling with sand. We came in and bombed them out in the first gulf war when we were dislodging the Iraqi military from Kuwait.
Also, supposedly the hangars would require too much effort to demolish or to repair, which is why they have been left in this state.
I don't know how much of that, if any, is true.