Im more of a mutt than my dog was when he was alive. Im like Half Half Half Half Half Half Half Elf/Orc/Pomeranian at this point with how much of a Mutt I am.
IIRC, from what I've read, it's to keep it similar to the system used in the actual Warhammer: The Old World miniature game which is also uses D10s.
Or is it WFRPG that uses D10s?