You know how easy it is to see into a lit house at night. In a night time secenario, if my home is being invaded I would want outside lights on and want to be able to see by the ambient light coming in.
You know how difficult it is to see out when the lights are on inside at night, right?
By the same token, bad guys can not see in if the lights are on outside and it is dark inside. I would take that advantage every time with the bad guy entering a dark space from a bright space and not able to see.