If we use the Bible as our guide, particularly the book of Acts, we see that the Apostles chose a council of equals to serve as the authority for doctrine.
The Ancient Christian Church continued that tradition when it used an Ecumenical Council to formally decide which books would comprise the New Testament.
Sounds good. I, for one, would like to see something like that. The problem is, because the RCC sees itself as the inheritor of apostolic authority (I'm willing to concede 3/4 of the argument to them, but not the other 1/4), they want everything to be on their terms. They have no intention (and you can see it in the responses from RCC members, here, too) of changing or modifying or even moderating any of their Catechism to accommodate ecumenism.
The position of the RCC when it comes to eccumenism seems to be..."why can't you all just become Catholics?". Somehow, I don't think that approach is going to get us anywhere.