User blog comment:Kirkburn/Syntax highlighting - helping you read and write code/@comment-452-20150408160608/@comment-126761-20150408174514

This was not a change in plan - it was simply the way in which the code was developed: the title of the ticket those diffs reference is "Wikitext highlighting should have user preference". As previously mentioned, the preference does not cover both because they are not the same thing - there is a very reasonable likelihood that a user who isn't keen on wikitext highlighting may still find CSS/JS highlighting very useful.

I do not have any ETA on a CSS/JS-specific preference.