The packager has been updated to work properly with signed extensions which are now required by Mozilla going forward. Additionally, most extensions will be copied instead of unzipped when it is installed in browser\extensions.
And don’t forget, if you want to automatically enable the extensions packaged with the Firefox Packager, please use lockPref(“extensions.autoDisableScopes”, 11); in the CFG Additions tab. Please see this great post by Mike Kaply for a complete explanation of the value. A value of 11 (1 + 2 + 8) leaves out 4 so the packaged extensions aren’t disabled automatically.