Prompting Passion?

I've always been puzzled by the concept of prompted recall that is so beloved of advertising agencies. To show the effectiveness of campaigns, they survey the awareness of the product/service or bizarrely, on some occasions, the advertising itself. In order to get a better number, they repeat the questions after prompting the poor forgetful consumer with various brand names.

Awareness of what you offer is obviously essential to generate interest in what you're selling, but prompted awareness hardly implies a passionate consumer so what's the point?