Got A Light? Origin of the Flashlight explains why we call them flashlights:
The tubular flashlight as we know it was invented in 1896 by David Misell. Before then people were left to very unsafe methods utilizing oil lamps for finding their way in the dark. Early flashlight models were very inefficient due to limitations in both battery and light bulb design. They were capable of producing only short pulses of light, hence the name flashlight.