It depends on the technology involved.
Any technology that can be applied to a bipedal robot can be applied to tanks, jet planes, and helio ships, so adding a mess of moving parts into the equation (like legs and arms) is a complication.
However, just what capabilities are we talking about when it comes to super metals? Can a robot made of super metal weighing a couple hundred tons with complicated parts like moving arms and legs strike the ground at terminal velocity with absolutely no threat to it's structure? If the answer is yes, then complicated war machines designed by mad men might be a requirement to dominate the future battle field.
However, keep in mind that any new technology could be applied to much more practical machines, namely tanks and jet planes.