Skirted sofas have a very practical purpose in terms of interior design. It's very possible for a space to be too "leggy", meaning a dominance of furniture legs in the room, and skirted sofas help to balance out that space. Skirted sofas act as a way to hide the legs, providing a more balanced visual aesthetic of the room. It breaks the room up a bit and keeps it from feeling like everything has legs of contrasting styles.
Shown: Nicolette Skirted Sofa by Jessica Charles