The point is that while it's not too much trouble to do as you did, it is often too much trouble to do it properly. Giving the OP some credit for being a reasonable programmer, your reply is less useful than it might at first appear.
Sure, it isn't too much trouble to instantiate a Random object, but to do it properly can be a right pain, and sometimes just isn't worth it.
My reply was a counter point to that statement, and not a discourse on using Random.