You should really consider adding a way to extract add-ons safely and simply in Firefox by opening the add-ons section and exporting add-ons so you can keep them in a safe place or manipulate them as you like so we can get the most usability from Firefox add-ons Some of them are ill really useful, and the developers decide to discontinue supporting them extracting them would be a excellent way to keep them and continue on developing them even after new versions of Firefox are getting released I think a good developer can extract information from the (.xpi) flies and work on developing new tools or continuing the good work of the others.
- I know there's a way of getting add-ons files from Firefox profiles, by finding the add-ons from there is like torture.