If I may play Devil's advocate here: Sounds as if Metcalf is making a common assumption that armed citizens in a self defense situation, should not be shooting through barriers. Ever! In some cases shooting at someone behind a barrier could be considered reckless, simply because there may be more folks (hostages, by-standers, etc.) behind the barrier, than just the shooter. If innocent lives are placed in danger, I would agree with his assumption. But as with many ass-umptions about shooting situations, there is no way to know. Sometimes it may be appropriate, but each event has to be judged on it's own merit.
Basic firearm safety rules demand that we should never shoot until our sights are on the target, and we are certain of our background. If our adversary is behind a wall, there is no way we can have him in our sights, and there is no way to be certain of who, or what else may be there.
Law enforcement folks need to follow the same basic safety rules as everyone else, because there is a lawyer attached to each and every bullet that leaves a gun, even a cop's gun. Maybe, especially a cop's gun.
I think what we are seeing is marketing hype on the part of Hornady. I like, and carry their product in some of my pistols. I presently carry Critical Defense in 3 calibers. I wonder if there is really a difference between Critical Defense and Critical Duty? If you can make someone believe they are getting a bite of the forbidden fruit, they will be willing to pay a higher price for it.