What are the difficulties with doing that? What's stopping that happening?
Leaving aside the structured-data thing (in the belief that it's not going to happen anytime soon), could we superficially improve the upload form?
Say, use Javascript to create form elements (text fields) for the various bits of {{information}}, and then do some Javascript warning if you hit 'Upload' but haven't filled one of them out?
Also, would this really solve anything? If you make fields mandatory don't people just lie to get past them? (which is kind of where we're at now.) After all you can require someone to fill out a field but you can't technically require someone to tell the truth (or even care).
In this case, the difference would not be so much in the technical bells and whistles than in the "shoot on sight" policy for images which don't have an author specified. A really convincing lie is probably as difficult to do than a Free image, so most people don't bother.
This being said, the "mandatory author", if considered, must be refined (else we'd have to get rid of most Egyptian antiques...). The strictest implementation I can imagine would be to require the name of the author for works published after a "safety time", a date before which works cannot possibly not be in the public domain by now (it's be in the 150 years order of magnitude, making provisions for the author living 80 years after he created the work and a 70-year delay for public domain. Beware, a 150-year provision does NOT take specifics into account, like the 30 year bonus for authors who "died for France". Count 200 years to be reasonably sure).
-- Rama