>>7775430It has to do with the joint connections and the pelvis. Frame arms did differentiate eventually by using less and less of the internal frame parts. I am not sure if Bandai will do that as their motto seems to be reusing the whole runner of structural parts for every bot design.
Some restrictions that I see are the length of the biceps, shape of the pelvis, shape of the waist.
Some things that are free to change would be anything in between any two joint part connections such as the forearms, thighs and lower legs.
Maybe we could get a long armed gorilla with short legs in an official capacity. Furthermore, much like Lego and Hexagear, users could build their own design beyond what is recommended.