The ships Paul Allen is finding now are far too deep for a plunderer to get to. 0n the other hand, USS Houston, which went down in relatively shallow Dutch East Indies waters, has been hit, as have many Dutch and British ships sunk by the Japanese invaders. I agree there is a special place in hell for people who toss what is in reality a war grave.
That's true for now. I'd guess there are fewer than 50 subs capable of dives below one mile, and there are damned few military subs that will go deeper than one half mile. But remote controlled, self-propelled, very deep-diving drones will be in the hundreds within perhaps five years.