The truth is, a sprinkler will control a fire with a tiny fraction of the water used by fire department hoses, primarily because it acts so much earlier. Automatic systems spray water only in the immediate area of the fire and can keep the fire from spreading, thus avoiding widespread water damage. Sprinklers go off accidentally, causing unnecessary water damage. Accidental water damage caused by automatic sprinkler systems is relatively rare. One study concluded that sprinkler accidents are generally less likely and less severe than mishaps involving standard home plumbing systems.
Sprinklers are ugly.
Sprinklers don't have to be unattractive. Pipes can be hidden behind ceilings or walls, and modern sprinklers can be inconspicuous - mounted almost flush with walls or ceilings. Some sprinklers can even be concealed.