The problem is that if pulling a firearm out of concealment and pointing it at someone is justified, unfortunately you will already be in a situation where you will need to fire the gun. If you are brandishing a weapon before you are in imminent danger of sustaining possibly life threatening physical harm, you are already breaking the law (generally speaking, and acknowledging that the laws vary from state to state and are inconsistently applied case by case).
Maybe some folks say "screw the law" and will brandish a firearm before they actually need to use it. Maybe this alleviates a worse situation, but my opinion is that it is still illegal.
Personally, I ignore anyone who are farther than about 15 feet away from me. If someone becomes physically violent with me within that distance, I'm not going to have any time for "show and tell". Just my thoughts - feel free to disagree.