We need structured data for media assets, but as you start to support different data types and relationships I always feel bad that we don't adopt a more general solution.
Additionally, the departure of wikitext based data has some consequences to list a few:
- You need separate api entry points for bots and applications to update and read things
- You need magic non-standard variables calls to access this data within wikitext for formatting and display
- Your wiki-page dumps don't include the data for that asset,
- The data is not easily integrated into templates flows
- the data lacks flexibility and is tied to a given interface and 'input/output' that is not easily generalized.
To me it seems we are so far down the rabbit hole of wikitext encapsulating both data and representation, that it will probably be better to concentrate on a general solution than building lots one-off solutions. If building one off solutions we should ideally try to keep some consistency with other structured data types ( like categories )
That being said there are of course some advantages of moving things out of wikitext and there is no perfect solution. Lacking a general solution, one-off solutions are better than ~no solution ;).