Haunted House by Sean MacEntee (cc by)
In short, it describes the interwar period as formative for creating the idea of the Gilded Age mansion as a place of mongrel (sic) agglutination in architecture and interior design, thus impure, and a sign of the excesses of the time, anti-industrial and anti-progress. In addition, there remains the idea of the grand old family and the secrets, hidden unhappiness, and isolation which may have remained in the childhood memories of artists creating in a post-WWI era - which has its own Zeitgeist, a combination of glitter and ennui/angst, both meanings of decadence. So by the 1930s the decrepit mansion 1. was actually decrepit when seen and 2. was not appropriate in several ways by economic/socio/cultural standards.
Citations and conjecture about why the Victorian house is always where the monsters live.