That would make official_name an exception among all the name keys – for the reason you describe, but still potentially surprising to existing software. There already is a poorly documented exception for names of public transit stations, where the subkey is an arbitrary acronym representing the transit system as a naming authority. Though this would provide authority-first flexibility, it’s also all but guaranteed to go unused, even by software that tries to use it.
I don’t really see verbosity as a problem here. Relatively few features need this kind of expressiveness, and some platforms even have built-in affordances for working with the standard IETF/UTC syntax.