It would be nice to have a real AppleScript dictionary in Firefox, like other Mac browsers have. It would be nice to be able to browse windows and tabs, and get the addresses…, in AppleScript. We can do that with Safari.
Agreed, I build a bunch of workflows around Chrome's AppleScript dictionary, and I haven't found a good way to migrate those over to Firefox. Most valuable to me would be exposing the browser's tabs and bookmarks to AppleScript.