As game designer and player I use a gamepad with triggers in my left hand for movement; forward, backward, jump, crouch, strafing, and other functions such as; use, flashlight, reload. I control firing and site with the mouse with my right hand. This is due mostly to having had carpo tunnel and my current arthritus. I found a nifty little FREE program called Xpadder that allows a person to map keyboard functions to a gamepad.
www.xpadder.com (site seems to be down at the time of this post)
So yes by all means add support for a gamepad too many games don't no days.