Specifically about the Five-Seven,
Forgive me if I make any technical errors - please correct me if I am wrong.
Anyway you try and justify it - it was designed specifically to defeat body armor. The military/police ammunition is illegal to own because it has a steel-core AP penetrator. Thing is, the cartridge was designed with more than one form of AP characteristic. Even with the civvie ammo available, small bullet diameter, as well as high velocity - works as a "vest-buster" regardless of bullet design in this cartridge.
Total hypothetical situation here. Our government becomes tyrannical. Say, like the Nazis of the 1930's. It is safe to say that the strong-arm of this tyranny will be the law-enforcement establishment. [please, no flames here - we all saw New Orleans]. These authorities WILL be wearing body armor. Either type IIa or IIIa.
If you had to engage them in self-defense against unjustfied arrest, imprisonment, or from extermination - your 45acp, 9mm, 38spl, 357 are all OBSOLETE. Preferably, you'd need to be using an AK, AR, M1A, FAL, M1 or whatever your fancy is. Unfortunately, you can't easily carry one of those around society or easily wield one from a car as you could a high-capacity pistol. It is out and about in society where "they" prefer to prey on you.
You have to compromise. I know you all want and like your 230gr .45acp's...but they are obsolete. They will not penetrate. They will knock the wind out of someone, but they won't take them out of the fight. In fights, ranges are short, 0ft to 21ft typical with 75ft max. At such ranges, speed is KING. You will not be making headshots unless you are Jerry Milucek (sp?)...You will be going for torso shots. Which are bigger and easier to hit in a defense scenario. They also contain the vitals needed to be hit for incapacitation.
The tiny Five-Seven ammo isn't a great round, but it at least "gets you in the game" by giving you the ability to actually wound the "opponent" in a serious way. And step 1 is body armor penetration. It's a compromise. It is a "work around" solution to a "problem"...
I know that isn't very politically correct, but oh well. Again, no one is discussing fighting the police or government. Only discussing the effectiveness of arms as DETERRENTS. And as we all know, for deterrents to be deterrents - they must work IF needed.