The main rationale for reverting to numbers required is to ease the task for Race officers of recording boats across the finish line and to ensure boats are identifiable in our various photographic media.
The main rationale for staying as we are now, with spinnakers allowed without numbers is ease of selling second hand spinnakers and use in different boats.
None of the above criteria are valid reasons, in my opinion, for the inconvenience and minor expense on putting numbers on spinnakers or sticking them back on when they fall off. After Medway my spinnaker shows ‘073’!
Modern asymmetric classes manage perfectly well without numbers on their spinnakers and we should follow their lead.