Зачем вообще может понадобиться передавать структуру?

using System;
class newClass
{
    public int n;
}
struct newStruct
{
    public int n;
}
class strucExer5
{
    public static void trackStruct(newStruct st)
    {
        st.n = 8;
    }
    public static void tracClass(newClass cl)
    {
        cl.n = 8;
    }
    public static void Main()
    {
        Console.Write("\n\nWhen a struct and a class instance is passed to a method :\n");
        Console.Write("--------------------------------------------------------------\n");      
        newStruct ns = new newStruct();
        newClass nc = new newClass();
        ns.n = 5;
        nc.n = 5;
//value of the struct field did not changed by passing its instance     
//because a copy of the struct was passed to the trackStruct method     
        trackStruct(ns);
//value of the class field changed by passing its instance
//because a reference to the class was passed to the tracClass method       
        tracClass(nc);
        Console.WriteLine("\nns.n = {0}", ns.n);
        Console.WriteLine("nc.n = {0}\n", nc.n);
    }
}