> Instead of giving users the choice to install this add-on, we initially pushed an update to Firefox that installed the “Looking Glass” add-on for English speaking users. This add-on was installed and set to ‘OFF’ and made no changes in the user experience unless it was explicitly turned on by a user, but it was added.

Why was this done over asking the user to install the add-on themselves? Given relatively few people were going to use this, why push it to every English speaking user? It's not like enabling an extension or installing one is much different in terms of UX but allowing the former is much more intrusive for everyone not interested in "Looking Glass".