I find it quite astonishing that I was actually pondering on this particular type of matter regarding bipedal robots, or more specifically humanoids, very recently.
Humanoids, given that their physical structure extensively resembles that of a human, are more suitable in operating in environments where humans would normally operate in. This alone has the potential to alleviate the tasks that would otherwise seem redundant and repetitive but also situations where it would be too dangerous for humans to work in.
Intrinsically, our environment is filled with objects that have been specifically designed for us to interact with. Whether it's the faucet in your sink, the knob at the door or the hand-drill, all these items have been designed for us to easily manipulate. Ideally if we want robots to operate in such an environment and utilize our tools, the robot would have to be built in a way that would allow it to accomplish such a feat in an efficient manner. Consequently the most viable robot that can satisfy these stipulations are humanoids.