Its used for two reasons, by two types of players:
1.) Those of the newer variety who are quick to overreact and cross controls.
2.) Those of the more experienced variety who understand that a negative-G avoidance maneuver is the last thing expected by other experienced players.
Generally concur with everything else written. Initially effective but purely defensive and, beyond the immediate avoidance, does not improve one's position relative to the attacking AC.
Waste of E.