The Bishop! And the Reformation "break"

One of my Presbyterian friends was just ordained an Elder in their church. This means he is part of the supervisory body of the New Brunswick Presbytery. He said to me: "Dude: I'm part of a bishop!"

Article 28 is a long one. There are many issues here I hope we may consider. But I wish to explore the fact that no bishops went over to the Reformation in Germany. In other countries only the Swedish bishops stayed (and I think the Finns?). This is a big deal from a Roman Catholic view and even causes trouble for Lutheran-Anglican relations.

For the sake of argument, let's say that the bishop is an important part of the church's apostlicity or even that it is a really good thing that a church must have to be the church. This apostolicity involves far more elements than the continuity of the bishops' office in the single act of laying on of hands. There is the fidelity of the people of God without whose help there would be no church. There is fidelity in pastoral practice, in social witness, there is liturgical and musical traditions, the Bible, and so on. Unless the bishop is so essential to the church that she is more important than the other elements of apostolic tradition, then why would a break in that signify a whole break? The Decree on Ecumenism states that such churches are "wounded" or "defective" (I'm not sure of the official translation). Would not a church be wounded that did not follow some of the reforms in other areas of apostolicity? Why is the bishop's office more or most important? Or is it better not to think this way?