Two advantages are that they are lead free and that the bullets are lighter making them easier to shoot. I think the jury is still out on effectiveness but most times the size of the wound channel isn't so important. FMJ bullets and these x-cross shapes are plenty deadly too.
I'm not saying you shouldn't use the best round, just that most always you didn't need to.
I'm not saying you shouldn't use the best round, just that most always you didn't need to.