<span>A combination of decreased homebuilding during the Depression and World War II coupled with the return of millions of veterans at the end of the war created the worst housing shortage in this country's history. Wilson Wyatt, the federal government's new Housing Expediter, estimated that 3 million houses needed to be built between 1946 and 1947. The demand for most of these homes was among low and middle income families. Many looked to prefabrication as a solution, believing that manufacturing and technical advances generated by the war would result in homes rolling off production lines by the million.</span>
I think it's because they didn't want it to be so easy for someone to step in and issue new decrees randomly. Everyone would need to agree, given that America runs on a democracy.