These men and their colleagues made up the "Chicago School" (who some say practised the "Commercial Style"), which stressed economy, simplicity and function.
Whether or not he actually said "God is in the details, " the deceptive simplicity (nothing is more difficult than simplicity) of his rigorously stripped-down style -- "almost nothing, " in his own words again -- suffered a dizzying decline from exquisite to pedestrian to irredeemably banal in the hands of those who exploited it as a cheap, uncomplicated and highly profitable way to put up big commercial buildings.