The ridiculous "FBI standard" of 12" penetration is for duty guns for law enforcement. That penetration standard helps ensure a bullet can pass through an outstretched arm and still reach vital areas. People carried and effectively used pocket guns successfully for many years before this "standard" came about, and in my opinion the standard is entirely misunderstood-and misused with defense guns.
Personally, I follow the FBI Standard simply because I want my firearm to be as certain as possible to stop a determined attacker.
Attackers tend to have their arms up in front of their chest regardless of whether they're throwing punches or wielding a weapon, so I want what I'm carrying to have enough penetration to reach their vitals after passing through their forearm.
If you think that's an unlikely scenario or that choosing ammo for self-defense that meats minimum FBI/IWBA Specifications, then that's your prerogative and I won't criticize you for it. Heck, the likelihood of any law-abiding citizen ever having to do more than draw a weapon to deter an attacker is pretty darn low to begin with, but it makes me feel safer knowing that my pistol absolutely can stop a determined attacker so long as my aim is true.
Besides, 12" of penetration isn't exactly a tall order. Ever a .22LR fired from a pistol will penetrate deeper than that with solid bullets, but when it comes to small caliber, lower power self-defense cartridges like .32 ACP and .380 ACP, JHP penetration can be sketchy. Yes, folks have successfully defended themselves for over a century using little .25 ACP pistols, but back then most folks used FMJ, so penetration wasn't an issue. Nowadays everyone uses JHP, so I just felt the need to point out that you might not get deep enough penetration to stop a determined attacker with just any .32 ACP JHP ammo.
Also, when folks ask for advice regarding self-defense, I take it very seriously, so I would rather suggest something that offers optimal effectiveness within the set parameters of the person who asked rather than simply tell them, "Meh, just use whatever, it'll probably work out just fine." I want better reassurance than that when it comes to my personal safety in a potential life or death scenario, and I'm pretty sure the TC does as well.