The cardboard corridors and rooms were always on the Enterprise. Those were reserved for enlisted crew at the bottom of the rank hierarchy, while the officers (and even cadet Uhura) got to work and live in the Apple store corridors and rooms.
Once Kirk got over, disgusted with the blatant elitism and disparity in interior design between officers and enlisted, he ordered that all corridors and rooms in the officer ranks be "downgraded" to the enlisted style to show equality among all the crew.
There, discrepancies resolved.