It is more than just the "look" of this building - although if you look closely there are some nice Art Deco features which landed it on the Philadelphia Register of Historic Places.
However...beyond the look of the building speaking to a certain era, some significant history surrounds the building. This Hidden City article does a great job of explaining - it was written when the former proposal was still around.
http://hiddencityphila.org/2014/05/p...1900-chestnut/
Basically - the building was built by an African American lawyer in 1935 after his current office space had been non-renewed and he was turned away from other Class A Office options on the basis of his skin color.
So...it isn't just the facade that is under consideration.