first of all, i don't think Handling is used in shot creation, it's only useful for preventing turnovers..
I think quite the opposite...Game manual is a bit vague on this, but I think Driving determines how often will player decide to take a shot, while handling will determine the quality of the shot, mainly off the dribble. I think Handling plays almost no role when a shot is taken after a pass and a great role if the shot is unassisted.
Of course I have no proof and maybe I'm just imagining things or comparing live basketball too much to BB. But for now, +2 in HA is same for me as +1 in JS and JR.