Why? The -one-true-church crowd are usually proponents of rigid and outdated doctrine and elitist triumphalism.  Dominion theology, in other words, which will NOT work in this modern age, nor should it... (yes, we live in a MODERN AGE--quite obviously--just like each civilization that has gone before us.) 

Your choices are to adapt to the prevailing ecumenical spirit, schism or form your own church, or just plain get out of the way.  The wheels of reform were set in motion at VII (actually 1517 if you want to be technical) and the reformed church simply has nothing to gain by employing heavy-handed, imperial-minded strategies of yesteryear.