Until April 2009 "most recently changed" was the default (and only) way favourites were ordered; then it was changed so that you can sort them by views/newest/votes.
I have some 170 questions favourited, many of which are very popular ones that keep popping up every once in a while. Now it's impossible to easily see which questions have new answers (or edits); you'd have to manually scan the dates in the favourite list to do that.
I consider favourites a list of stuff I've marked as interesting, something I'm tracking, and I'd think I wasn't alone with the habit of browsing SO by checking which of those questions have new answers.
So I propose that "recently-changed" ordering is re-added, along with the current options. What do you think?
Edit: as indicated here, this feature has been implemented: there's now "recent" among the sort options on the favourites page. :-) As a bonus, user's own questions and answers can also be sorted this way. Thanks to everyone involved!