As far as I know this idea has not been mentioned before. I would find it helpful on the photo management page to be able to sort photos by number of keywords (asc, desc), to see at a glance which photos need some more attention as far as tagging is concerned.
Nothing to hurry about, but it is a nice-to-have-feature :)
Nice feature request. Maybe also a function which van sort on amount of comments?
keywords are the life to an image bank. there would be a number of good images but inadequate keywords, or wrong keywords, inappropriate ones, or just plain lack of keywords affecting the search function, and you'd have a poor search result, despite having a great image collection.