Asymmetric key management

Now that we see the full detail of interactions required to verify a
single message, I wonder if there was ever a time when the advantage of
asymmetric versus symmetric key management was laid out.  If anyone has
an on-line reference to that decision, I would like to read it.  As it
appears from what has been dispalyed in the last several days, symmetric
key management just might be simpler to implement and to user.