I find the use of frames very useful and specially like the ability to use the frame panel to quickly navigate from frame to frame.
I think it would be very useful to add the ability to have the frame outline use indentation for embedded frames. This would allow users to compartmentalize related concepts. Add the ability to sort frames alphabetically and now you have a very useful and friendly way to move from frame to frame in large diagrams.
Not just indentation but ability to collapse and expand as a hierarchical Table of Contents
Also allow a frame to be in the hierarchy more than once and at different levels