I wouldn't say this is exclusive to robots or new. Many machines, like cars, are referred to with a feminine persona: she's really humming (in reference to an e

I wouldn't say this is exclusive to robots or new. Many machines, like cars, are referred to with a feminine persona: she's really humming (in reference to an engine), come on old girl. See also the many boats throughout history with female names. That doesn't get me any closer to why, but I would say for robots, it would seem rooted in this tradition. They're just another kind of machine.