As I understand it the empty backfield forces the defense to declare their assignments pre-snap, making it easier for the QB to read the defense and determine ahead of time where the open receiver is likely to be.
I have a faint memory from the GSOT days, after Martz became the HC. Martz was getting some heat in the press for running a play out of the empty set in the red zone, the complaint based on the fact that the threat of the run had been removed. Warner chimed in and said that he preferred the empty set in that situation, basically for the reason I described.
AlbaNY_Ram
