Devs can make JHP to have +crit chance/roll, which is realistic. And it can be made to be better than AP against metal and worse, which is again realistic, since metal armor covers only your chest and feet. Against CA+ it can be just a little worse with raw damage, but +crit may work as alternative. 5mm JHP must have -DT and -DR, or else it won't be used, which is, ironically, again realistic, as low caliber ammo is always good against armor, since anti-bullet armor uses bullet's blunt force and spreads it on larger area, rather than stops its penetration, that's why you can kill cop with an arrow in the chest, but can't with low power handgun.
In the end it's possible to make JHP useful and at the same time not break logic. So against CA+ (metal for mutants) it'll be choice between damage and critical, and for metal and worse (leather for mutants) JHP will always be better.
The only problem I see, is that when there be wipe and again all that tech progression, people simply won't use AP ammo for a long time, since no one will have CA. So it'll be the same problem as it's now with JHP, but with AP. May be give AP ammo some bonus, if it reduces target's DR to <0%, so it will also be an alternative to JHP even against low armor targets. May be JHP always +crit and AP +crit roll, if target's DR is low.