Electric coolers keep things that are already cold, cold. They do not re-chill things that are warm.
Disney installed these for a few reasons. Beverage coolers do not use the electricity that regular half size refrigerators consume.
The staff to continue to coordinate picking up and delivering the old tiny fridges to the room is unbelievable.
The staff needed to physically deliver the units and lost time due to back injuries.
The cost for storage of the units in a climate controlled environment vs. Keeping them in the room.
It is a no-brainer.