I wasn't around, or at least very active in the roleplay community, when the hub was N/Z. However, if there ever were to be a change, I predict it to be the Temple of Dreams portal. It's rather easy to find, and just about everyone who regulars Fluorite knows where it is.
As for the change, it does seem as though N/Z would have been a bit problematic for large groups that like to drag all online members to recruit. People would likely have to all pile on top of each other to stay on the hill if their line was at an angle, and some might just give up and sit down at the base of hill. I believe that they just scooted over to the bridge because it was a more flat area, so larger groups could spread out a bit more and not be all on top of each other.