This is a vast subject and Jon Stokes touches on some of the reasons people would need or want to use the AR15 platform. This is mandatory reading for anyone who has used this rhetoric.
“Nobody needs one of these weapons of war”, is the common refrain. Yet, some 5 million Americans have decided that they do, in fact, “need” an AR-15.
“Thus it is that since the dawn of the gunpowder age, gun buyers have snapped up military hardware.”
“The AR-15 is less a model of rifle than it is an open-source, modular weapons platform that can be customized for a whole range of applications… the AR-15 is basically a giant lego kit for grownups.”
read more:
https://medium.com/@jonst0kes/why-i-need-an-ar-15-832e05ae801c