Binary transparency seems to be a nice thing to have though quite limited in scope for linux as distro usually compile from source. Even more limited as mozilla knowingly makes controversial choice stating unhappy users and distro can recompile with a build flag until we strip the code.
IMHO mozilla should orient its transparency effort towards its decision process first so we don't end with a binary transparent browser no one use because management decided to remove user choice and break the UI (to look more like chrome), break extensions that contributed to firefox success (to be more like chrome), require pulseaudio and drop alsa and so on.
All the examples you mentioned were communicated pretty transparently in Bugzilla, developer blog posts and announcement blog posts. Just because you disagreed with them doesn't mean that the reasoning wasn't public and that you couldn't have contributed to it.
IMHO mozilla should orient its transparency effort towards its decision process first so we don't end with a binary transparent browser no one use because management decided to remove user choice and break the UI (to look more like chrome), break extensions that contributed to firefox success (to be more like chrome), require pulseaudio and drop alsa and so on.