Why do hotels think guests want access to ice in their rooms?

From housekeeping service to a Bible in the nightstand drawer, there’s a standard set of amenities you can expect to find in most American hotels. We can chalk up housekeeping to hospitality and Bibles to the Gideons, but what about ice machines—how did these hulking apparatuses come to be so common in the alcoves of American hotel hallways? Sure, ice is theoretically useful, but who decided that hotel guests must have free access to it at all times?