If by excommunication you mean the practice of church discipline whereby an unrepentant member has been confronted and is removed from the local assembly, then it is for today and there is no justification for excluding it (remember the often quoted phrase "when two are gathered in my name"?...the context is church discipline).
It should be handled in accordance with Scripture. I'm not sure what you mean about hierarchical power, but if there is no grace in it then it is not biblical. The grace is that this is done in love with the purpose of saving or bring back a brother. The grace is also in it as this keeps sin out of the church and looks to the care of other members.
