The Cincinnati Zoo was willing to expand the viewing deck of Giraffe Ridge many years ago, in addition to a presumed expansion of the yard. Modifying existing exhibits despite being relatively new is nothing new for Cincinnati. Additions such as a "pride rock" in the lion habitat, an artificial tree in one of the tiger yards and the snow leopard habitat in in Cat Canyon, among others have been prevalent throughout the "More Home to Roam" campaign. Because giraffes naturally thematically tie to Africa, an expansion of the barn is necessary as well as feasible. It could be under the premise that the zoo would want to expand its giraffe herd, following the motif of "More Home to Roam". (What potential is there for expanding the Hippo Cove area as well?)
As for the whole reptile house argument, if a zoo wants to present reptiles in an engaging way, they need to do away with long, nondescript hallways. Fort Worth went amazingly creative with MOLA, Los Angeles has the LAIR, Atlanta has Scaly, Slimy, Spectacular!, and now Zoo Knoxville has the ARC. Ed Maruska, Cincinnati's former director has expressed want for a new reptile building, however he couldn't find enough people/higher-ups who would be interested in such a project.