It is possible the grips were inspired by the configuration of aftermarket grips that featured the finger contours, and the clear plastic grips on the innovative (at the time) ASP pistol. In my opinion, the Bladerunner pistol utilized so many clever and innovative features that it will remain as one of the most popular movie guns of all time. There are still some mysteries as to the design, such as how was it supposed to function? Revolver function seems straightforward, but what about the rifle and the mag under the barrel? Innovation, appealing design, mystery...all cool.
Some of the Bladerunner uber researchers may have some ideas as to the origins of the grips.