I had to leave home in the middle of making a bunch of relationship edits, and my computer crashed while I was out (total fluke, my system is normally very stable). Now I have to re-enter all of them. Not the first time I've had this kind of problem... accidentally close a browser tab or window, click a link to another page, reload the page, software or computer crash, and you can lose an hour or more of work. Relationships and track lists are the worst, because they're the most likely to include a bunch of edits at once, where saving part way through could cause conflicts or incorrect edits.

(The automatic part is secondary, but would be really nice.)