What are your thoughts on Wikidata:Property_proposal/Wikipedia_infobox_field? There two main differences to yours:
- it's limited to Wikipedia (otherwise a selection isn't easily possible). Other projects would need separate properties, but I doubt that are too many that actuallly will.
- it's used as main value rather than as qualifier (too many qualifiers on a single value tend to get hard to edit in Wikidata).
Maybe there are other aspects I missed.