A bit late but it just dawned on me why the cars-as-robots idea made money while the furniture-as-robots idea won't work. The concepts of
"cars" and "robots" have largely overlapping connotations: speed, adventure, machanics, control, mastery, so one idea flows naturally into another. Then ask yourself, what are the connotations of "furniture"? Or put this another way, what are the ideas that Ikea ads sell? Comfort, a sense of place, belongings, personality. These have nothing to do with robots and no audience will identify with such a pairing.