If it is so good, and offered a clear advantage, wouldn't the FBI and LE still be using it???
Because most of us are civilians, not LE or FBI who want something that will shoot through windshields, car doors, etc. We civilians in an act of "self-defense", have no reason or need (or buisness) to be shooting through barriers...if there is a barrier between your "attacker" and you, one would be better off running away. LE and FBI do not have that option therefore, they adopted a cartridge that performs better at penetration of hard objects with less consideration on a "soft" target as a civilian would.