"Walls do more than just separate spaces," writes furniture designer Junichiro Oshima. He's speaking specifically of his A Wall line of furniture, which relies on a vertical plane to provide the third and fourth legs of each piece.
"[It provides a place to put] your favorite posters and memos."
"It can be used as a background to make things stand out."
"It also acts as a leg to support the furniture."
"A Wall adds a freely editable wall to the room."
"This is a proposal that expands the possibilities of living."
I think the concept is interesting,but far more context-dependent and thus limiting than ordinary furniture. For instance, I'd have been happy to try out pieces like this in my New York loft, which was vast and spacious; but these would never fly in the small and conventional house I live in now, where space is at a premium and "flow" is dictated by doorways.
I think these might find some success if sold without their walls, and with mounting kits to attach to existing walls.