Justification
One motivation for making humanoid robots can be understood in the book Philosophy in the Flesh by Mark Johnson and George Lakoff. They argue that the contents of human thoughts are to some degree dependent on the physical structure of our brains. By constructing artificial intelligence systems that have structural features similar to those of humans, we may be more likely to achieve human-like functionality.
Another motivation for building humanoid robotic systems is that a machine with a human-like form may have more human-like interactions with people. This could be particularly important for an artificial intelligence device to learn from people in the way that human children learn through interactions within a social group.
Read more about this topic: Cog (project)