Theory is great, but if push come to shove and it gets implemented it would only amount to extra entities with flavor text, modified behavior and maybe some extra attacks and modified stats.
Don’t get me wrong, this is also a major step forward, but for me (a game mechanic complexity maniac) what really stands in the way of fully utilizing this idea is the lack of proper anatomy system like the one in DF.
Having to aim for abdomen because an animal mutated to have thick carapace covering most of its skin? Parasitic cancer-like growth taking over circulatory system if its host heart gets shot? Tough luck.
That said I realize it is borderline impossible to simulate all this goodness on the scale the game takes place without slowing it to play-by-email turn-based grand strategy pace.
EDIT: Rimworld-like anatomy system would be more than enough, but I doubt even it would be able stand a chance, performance-wise, against a frag grenade in midst of 100 zombies or other creatures.