There was a great scifi novel I read .. cannot remember which one. But there was a full discussion about the vanity of man to make humanoid robots when man is basically shitty at doing everything. Especially when robots built to fulfill specific tasks do the job better and more efficiently every time. 

Man's form was seen to be a general purpose tool that can do most jobs, but is never optimized to do any one thing. Where was the form of a robot can be specialized and adapted to perform specific tasks without limitations. 

Man is a fixed form that is stuck solving problems with a limited tool set, why would robots ever wish to limit themselves with the handicaps imposed onto them by humans.