A "packer" isnt needed... additional usage of another program just to get a plane/object into the game... no. Many already struggle with the weapon editors
All add-on objects must go directly into their respective folders... theres no reason to pack them away into a single big file - that would making personal edits/ improvments/ fixes to them more complicicated, ect ect.
What would be good is a improved extractor, which allows to mark multiple files and then extract them all at once and perhaps to a destination of your own chice.
Skypat's extractor allows only extraction of single files or of the complete cat into the same directory where the .cat is located.