Per broad global consensus at https://meta.wikimedia.org/w/index.php?title=Wikimedia_Forum&oldid=11628429#Proposal:_restore_normal_editing_permissions_on_all_mobile_sites (see "Conclusion" for the summary) and per the closure of T55069, it's been decided to set $wgMFEditorOptions['anonymousEditing'] on all wikis.
The request is to get this done by the end of March, with a preference for getting T54165 fixed as soon as possible.
From an operational perspective, it may be advisable to have a staggered release, perhaps by triggering the configuration change in correspondence with the enabling of 1.25wmf23 (between Wednesday, 25 March 2015 and Wednesday, 1 April 2015). By not purging the caches, the effect will be gradual; while purging the caches would be required if site-wide consistency is desired. Either way, the effects in terms of traffic are negligible, based on it.wikipedia's experience (and even in case of a difference of one order of magnitude in other wikis).