Judging by how it is only partially rebuilt as show by the piles of rubble blocking off certain sections one could assume that the ceiling in the Council chamber has just not bee finished yet. If you look at the two pictures that you posted you will see that the basic design of the building is exactly the same in the before and after photos. I would guess that if the building were to be completely finished it would likely look almost exactly the same as in the original.
Anyway, I like the original, because it's finished. "