One word that comes to mind is telemetry. Now that they made the FHSS system faster than FASST, the one selling point that stands out is the telemetry capabilities. The other advantages of FASST is the distance and stronger against interferences, but as an on-road driver, I never experienced any problems with the FHSS system. Maybe if you fly it might be of concern. Hence they probably decided to go with the improved FHSS with the pistol style flagship surface Tx.