Socially, the Add Media Wizard is right direction, but it handles the workflow of inserting already available resources, it does not involve the scope of people able to contribute images.
What I describe is like combining this directly with the upload, i.e. add the newly contributed media directly to a page in a preliminary fashion. From a user view, uploading an image suddenly breaks context, and it takes a lot of mediawiki mastery to put the uploaded image into context. Doing half of this work lets the media contributing user have success, and distributes work better according to abilities (all collaborators knowing mediawiki markup or project rules can review contributed images and put them into place or even remove again).
Providing an extension that seamlessly integrates with upload wizard would be a huge achievement!
Gregor