The purpose is for the cadets to have a better understanding of the history of the infantryman and where some of the practices that we still use today come from.
Just because they are old does not mean they are not lethal.
This is a way to keep history alive.
The more primitive weapons teach what soldiers are supposed to do with the modern weapon.
If one of our troops has a malfunction or runs out of ammunition, he or she can still continue the engagement with opposition weaponry if they know how to use it.