This was an interesting comment from WhatamIdoing on T69826, so I thought I'd split it out for its own discussion.
Changing default user preferences means overriding the choices of
registered editors who actually want the feature (including thousands of
editors who voluntarily opted-in before MediaViewer was made avaialble
by default).It's too bad that MediaWiki doesn't have a good one-click system for
changing prefs, like a "Click here to enable X" button or pop-up. It'd be
so much easier than telling hundreds of users "Go to Special:Preferences,
click to this tab, scroll halfway down, find this item, tick the box, scroll
all the way down, save the page."
See Also: