Ummm why not? Gun users would finally be able to have ammo that makes sense for their build style. Yeah armour pen would be ideal for most people. But you would have a choice.

Maybe as a commando build using ammo does more when hitting in vats would be better off over armour pen. Or as a heavy gunner hitting body shots is more their style. Or as a sniper getting head shots is more your style.

Having the choice is always better than defaulting to the same thing as everyone else or because there’s simply nothing better.

Saying we don’t need it because people won’t use it is never the outlook to have. Just slapping perforating on it and calling it a day just puts us back to where we are now next Tuesday.