Does This Trope Exist?

It always bugged me that often times only characters that are made of metal or can regenerate lose their body parts. This goes from Dragon Ball where Picollo constantly loses limbs to Iron Man where people who are made of flesh do not lose limbs but his armor gets destroyed all the time when fighting against flesh. I realize that this avoids having a lot of amputees on a show/book but I often find this a poor plot device. Anyway, is there a page for this? There should be.

See Good Thing You Can Heal and Healing Factor.

And I don't really consider this to be an bad plot device if it's being used to trick an omnicidal monster into spilling his evil plan before he kills you, then regenerating your arm to troll him into retreating.