It would be very useful, if Rhino could get an Object Manager (Outliner) like it was developed as an experimental plugin for Rhino4 some years ago.
I often work with large Rhino files with thousands of objects on many layers. It’s very hard to look for an object that is hidden, when you don’t know on which layer (some are turned “off”, some are turned “on”) it is placed. Seeing which objects are members of a group or block is another missing feature that an object manager could enable.
This object manager could also be very handy to organize the file structure by dragging and dropping parts or groups from one layer to another.