How about if you have a wall-mounted flatpanel TV and don't have space underneath it for a set-top box?
This way you could have the set-top box mounted, say, under the sofa (which would be rather practical with some DVD players- you'd not have to walk across the room to change DVD). Now with a single set-top box this may not seem like much, but if you had a sleek wall mounted TV and had to then find space for an XBox 360, PS2, HTPC, Wii, SKYHD box and whatever comes along in the future... well, you'd probably appreciate having these things tucked neatly away under a coffee table or whatever rather than piled up at the bottom of the wall. And the huge bundle of cables could be condensed down to a single wireless link and a multi-input switcher.
Plus, as it's broadcast radio, you could have a wireless digital link to your speakers rather than running cables/fibres (which can look really messy).
Alternatively it could probably pass through a thin wall with a receiver and transmitter blutacked to the wall itself (i.e. with bugger all distance between them) and this could be preferable to drilling holes in walls in rented accommodation.
And there are probably 1001 other uses no-one's even thought of yet.