This assumes that (1) HTML rendering is dropped (e.g., no more "HTML if possible"), and (2) it is considered acceptable to download images just to replace them shortly after, e.g., by MathJax output.
Topic on Talk:Requests for comment/Reduce math rendering preferences 2
This post was hidden by 66.154.186.32 (history)
This option shouldn't be removed, since it has a significant and well-defined functionality, which doesn't hurt anyone and is useful to a few people.
When i replied about it on wikitech-l, i knew one university professor that used it. Since then i found one more such person.
In fact, you can just check how many people actually use it (in each of the 800+ projects). If it's more than zero, keep it.