Problem: Ugly links in wikitext, internal links showing as external
Proposed solution: Allow a preference to add a checkbox next to the edit summary. This option would transform links (and possibly do minor formatting changes like convert dashes and under scores) on preview and save. Example of what can be done.
Who would benefit: Wikitext readers, reducing maintenance edits (see example link above) would reduce the total number of edits and thus edit patrolling.