OK. The Question is: Do you think that a Giant Fighting Robot would have any value in real world combat? Assume that it doesn't contain any unknown Technologies (Such as Mobile Suits being powered by Fusion reactors), although the application of new technologies like Carbon Nanoutubes is fine.
I personally think that terrestrially, a bipedal fighting unit of any height greater then 10 feet would be useless. Tanks and Mobile Artillery can go practically anywhere as it is, and have a great advantage in being close to the ground, which makes them much harder to spot. Any decent Air Force would have no problem annihilating a 30ft walking mech. It's large, expensive, and an easy target. Walking Powered suits could have some large advantages for infantry and engineering units, but as a replacement for Armored Calvary, or Artillery? Please.
However, in large scale space combat, the mech becomes a lot more viable. Compared to a Ball-type space combat vehicle, a bipedal mech with thrusters mounted in the shoulders and feet would be relatively easy to control, essentially using the mech’s legs to control the direction of the jets, allowing more erratic movements and less computer control. Also, the reduction in the number of jets needed to maneuver would make the bipedal mech cheaper. Compared to other vehicles, a mech with hands would have the ability to quickly switch weapons, and reload munitions by itself.