It would be very fun. Like Forgotten Beasts from Dwarf Fortress. It has no brain or heart, so you cant kill it so easily. 
And as I played Cata, I was wondering why player and NPC have head-arms-legs and zombies dont. It would be fair if everything would have body parts. Then if certain part is damaged smth could flee. Or how about a robot with disabled weapons? Come closer and hack it with your laptop!
Zombies could come with already hurt\missing parts so you can kill them as easy as now.
