I guess it could be useful for 1) tethered studio operation, 2) wireless transmitting of photos (Nikon and Canon wireless transmitters)
In both setups you basically have a "hot" folder into which are falling photos from some source as they are shot.
I can see the benefit of this for studios and agencies with a photo editor on site getting fresh photos from say a football game from several photographers. The Live Ingest would allow them to caption the photos automatically (i.e. filling the Author field for all photographers using code replacement from their cameras serial numbers).
Yes, I can see the usefulness of this, though not for me