they arent all really "unsighted", although you arent actually getting a traditional sight picture. With the gun up in the periphery below your line of sight, or your body indexed, your brain is getting a subconscious sight picture of sorts, and is aiming the gun, just not doing so in a manner most target shooters think.
If the gun is in front of my face why would I not use the sights, especially when a single round is most likely not going to stop the threat? Also if the gun is below the line of sight how can there be any kind is sight picture? Sight picture is most commonly defined as seeing the front sight with the top of the front sight even across the top of the rear sight having equal lines of light on both sides centered on the target.
As far as Rob and USPSA there are plenty of stages that the shooting box is one large area and the stage says engage T1 -T whatever as they appear. This allows for open interpretation and allows shooter to shoot the stage as they best see fit which does mean shooting on the move. But again even up close targets that are three yards and less your top shouters will still use their sights.