We see this horrifically realized in the Psycho Zaku. It is a towering junk golem, barely holding together, fueled by the literal blood and nervous system of its pilot. When Daryl plugs in, the machine becomes his body. The tragedy is that the closer he gets to "perfection" as a pilot, the further he drifts from being a man. He wins the battle but loses himself in the machinery.
The Zeon pilots of the Living Dead Division are not volunteers in the traditional sense; they are resources stripped of their autonomy. The mobile suits require direct nerve connections, and to pilot one effectively, you must remove the interference of flesh and bone. This is a stark commentary on the Zeon philosophy: the ultimate sacrifice for the collective, the literal cannibalization of the self for the state. mobile suit gundam thunderbolt december sky