Maybe because they forgot to program the tuner to record it?
I would have been more impressed if they slapped in a Digital HD tuner card and some basic software to time record events. If users cant figure out how to program the tuner to record shows (some people cant even figure out how to download MP3s illegally) they can buy them from Apple. Who cares if the quality is worse than analog TV, its hassle free.
I would never buy a Mac for this purpose. MyHD records, XBMC Plays and for alot less than a Mac Mini, even if it had a HD Tuner.