DARPA (the U.S.’s Defense Advanced Research Projects Agency) wants to make robots last longer (currently they can live 10-20 minutes without a power cord). This can be useful when sending robots in hazardous situations (like defusing bombs, rescuing people in a fire, cleaning up nuclear waste).
If you think even further, efficient, intelligent robots can free most people from jobs we don’t want to do, like menial, repetitive work, the kind that drives Foxconn employees to riot and commit suicide because of the subhuman conditions they have to endure manufacturing iPhones and iPads.
Hopefully, the unwanted labor can be shunted to robots, and people will be left doing creative and uplifting work, work people want to do, instead of work people have to do because they have to make a living to support themselves.
However, as any science-fiction enthusiast knows, the more powerful and intelligent we make robots, the more likely they can achieve sentience, which, to some people, makes them qualified for human rights. And their forced servitude, without compensation, will be tantamount to slavery. So naturally, we have to give them equal rights and citizenship, and all those robots will be competing with us for jobs (and they might be more tireless, powerful and efficient at it than us).
Leaving us again without anyone but ourselves to do the gruntwork.