Function pointers - why, when I can do without?

Disclaimer: I've read countless other articles on this topic and I still don't get them. Example: why do this:

void func(int a, void (*callback)(int))
{
    /* do something with a and callback */
    callback(3);
}

void pointme(int b)
{
    /* do something with b */
}

int main()
{
    void (*pf)(int);
    pf = &pointme;
    func(10, pf);
}

when I can simply do this:

void func(int a)
{
    pointme(3);
    /* do something with a*/
}

void pointme(int b)
{
    /* do something with b */
}

int main()
{
    func(10);
}

??? I really don't get it. Any help would be super-appreciated. Thanks!!!