Look, this is completely speculative. May have no scientific backing or value whatsoever, but here's a thought I floated during a conversation on TribeNet :
Mobile users love to accessorize : buying ring-tones, screen savers etc. There's a communication channel that tells people how they get these things. It would ironic, but horribly plausible, if there were people who couldn't find or understand the option on an obscure menu but could find it as a paid downoadable "upgrade" in a catalogue. Maybe that's the way to get it to them. Maybe the market is the easiest user interface?
See also :