I've learned from experience that characters who will appear as a group should be designed as a group, a certain dynamic needs to be built right in from the begining. You'll note that even though all these characters have a similar attitude (sad), they each have a unique heighth and shape, and no individual is distractingly more detailed than the others. This way the group reads quickly as a unit, instead of a chaotic mass of individuals. Hopefully.
These special pose sketches give the animators more information about how to use the designs.