Keep in mind that when the photo was taken (1920s-30s) and is in southern Utah, in the desert. By the 20s the town was rapidly in decline, severe droughts had destroyed the farming economy. Just like the Dustbowl, the photos even remind me of Dorthea Lang Photos of the Dustbowl disaster. I wonder if it wasn't taken in a similar project by the government.
Also keep in mind that Post Offices at the time were often "contracted" affairs, not run by the USPS, but by the lowest bid, or by public appointment (usually payback for political contributions). Many POs around our area were in people's private homes!
So, when wondering why the place was in a state of disrepair, take into consideration the state of affairs in town. It is a great building with much character. I am so glad that you found it and shared it! Might have to model it, it begs. I like the snow on the ground, nice touch.
____________________ Steven B.
Humboldt & Toiyabe Rwy