To answer your point about "basic categorisation of the nature of edits" I have two words for you: Revision Scoring
As Adam Wight pointed out at https://meta.wikimedia.org/wiki/Research_talk:Revision_scoring_as_a_service#... the Mediawiki system doesn't allow the editor to categorize their reason for reverting, so currently revision scoring as a service will not actually categorize the nature of what it is learning.
Supervised learning tasks have the ability to include such categories, and although something derived from the ontology at https://en.wikipedia.org/wiki/Wikipedia:Edit_summary_legend will be selectable, probably from radio buttons or a pull-down menu, during the http://mediawiki.org/wiki/Accuracy_review pilot, there will still be an "other" catch-all option.