Dennis,
I like your call for a collective discernment.  The truth is,  I think that's begun, but in less organized, more personal manner.  THAT's why there is a need for that "collective" word in this process.  
BB1958 made the comment that (s)he had chosen to follow conscience.  I think many others have done so, and that's why so many have left. 

I cannot help but recall the excitement around Vatican II.  For young people like me in those days, this wasn't about doctrine, history, or ANY real teaching.  Rather, it was about a new vision of church: a church that wanted to change the world by engaging in it.  We saw a church that finally willing to admit that it did not have all the answers, but instead seemed willing to trust the wisdom and experience of the laity.  We envisioned theologians begin able to push the limits of human thoughts, to ask those "what if" questions.  All of this (and more) was, I think what you called "collective discernment."  Imagine what could have been...