That doesn't make sense. You're saying that because they don't run more of the offense through him, he's unable to make more shots than he takes? What about Leonard in the post? He's also very good at scoring from there, but Pop almost never called plays for it. Green's supposed to hit spot-up threes, just like Leonard. Kawhi is better at driving when he doesn't get a good shot, and Green is better at getting open, so he didn't have to drive as much. In general Green has hit off the dribble pretty reliably. But if Danny just walked down the court and jacked up a three with 20 seconds left on the shot clock, Pop would pull him out.
You're suffering from confirmation bias. Green can shoot off the dribble, but because you don't believe he can, you forget the times he does. In actuality, Green shot an above-average percentage from two last season. But I bet you wouldn't have guessed that.