Some thoughts on:
https://www.mediawiki.org/wiki/Requests_for_comment/Core_user_preferences
and associated patchsets:
https://gerrit.wikimedia.org/r/#/c/27259/ https://gerrit.wikimedia.org/r/#/c/27258/ https://gerrit.wikimedia.org/r/#/c/27257/ https://gerrit.wikimedia.org/r/#/c/27197/ https://gerrit.wikimedia.org/r/#/c/27206/ https://gerrit.wikimedia.org/r/#/c/27202/ https://gerrit.wikimedia.org/r/#/c/27201/
I'm 100% in favor of de-cluttering prefs. IMO this ought to be done on the basis of proper metrics of current usage, so that we actually understand who is using these options today and why.
Do we have a more complete report than https://en.wikipedia.org/wiki/Wikipedia:Database_reports/User_preferences ? If not, could someone pull one? It would be ideal to not only have prefs listed by frequency, but to also exclude users from the set who've not been recently active.
Erik