The "TOP DOWN" model is necessary to the church and is a reflection of the church's self-understanding of the nature of its authority and function within the church community. Democratic or congregationalist models of church governance are incompatible with Catholicism. 

Christ appointed and gave authority to a clearly defined group of followers--the 12 apostles. He did not leave the question of authority to the community so that the whole community might at a later date determine its internal organization and formal constitution.  Even as the holy spirit decended upon the community at Pentacost, this authoritative structure as it existed among the 12 was already recognized and operating. 

What does it mean to say that the voice of the laity needs to be heard in decisions. Do you mean the 1 billion souls that make up the laity. What possible good could come from such a mixture of people.