The answer is: dramatize the stories narrated in the decorative programs of temples and sanctuaries.
contrapposto, or weight-shift Are mostly needed in creating 3 dimensional artwork (such as statues or buildings).
In its earliest development, Such statues are used for religious purposes. They often located near temples and sanctuaries in order to dramatize the accomplishments of deceased that deemed to have contributed a lot to society (such as dead kings or generals)