Appeal

From Anipedia

Appeal is one of the 12 Principles of Animation. Appeal refers to design in which anything that is animated should have a design which is interesting to the eye. A significant factor in appeal is the silhouette of the character or the object. Symmetry tends to weaken appeal, as characters that would look no different split in half and mirrored tend to be less like the real world and therefore strike some as unnatural or strange.