text: A priest does not have to run the business end of things in a parish or be in charge of that.  However, the Catholic Church tried the more "democratic" Protestant "trustee" model and it was a disaster.  That is why we have the system as we have it now.  What happens when the priest wants or needs to preach on something politically not popular?  The trustees would run him out of town--as they do in the Protestant Church.  I have seen many a Protestant minister destroyed by the trustees.  The minister becomes little more than a figure head with a trustee model.  The model is great in theory, in practice it is a disaster.  
  
  If all you want is a Liturgy of the Word with distribution of Holy Communion, all that is needed is a lay person.  However, if you want the Sacraments of Confession, the Mass celebrated, Anointing of the sick, Confirmation, etc, you would need an ordained priest or bishop.