Both our cybernetics and genetic modification technology are highly advanced. Most commonly, they are used to help people with medical problems.

The uncommon form, on the other hand, is used only by highly specialized professionals, those who can afford it, and the most elite of soldiers. A modifier body can greatly increase your strength and skill, and let you pilot much more powerful mecha - not just mass-produced machines, but customized engines of destruction!

It also completely changes your appearance. I wasn't even humanoid before I joined the military.