Just kidding.

I've read a lot of reasons / explanations. None of them make sense based upon the way we tried to fight in VN.

You have to remember we were moving toward a conscript military (like Russia) with less trained soldiers. Fire superiority seemed important at the time..instead of accurate deadly fire.

We learned about mass communist attacks in Korea, and decided wounding the enemy took two soldiers out of battle instead of just killing one.

Etc etc.

I'm not in the infantry, and will never be fighting off hordes of zombies (much to the chagrin of some here ). As such, I want ballistic superiority. I want the ability to punch through light armor, stop vehicles, and make the bad guy DEAD RIGHT THERE.