It's just a historical tradition isn't it ? I can't see any musical need for it but if you enjoy keeping track of these things then do it. Labelling my own music in this way would seem like cluttering it with useless facts but I have a composer friend who gets pleasure out of doing it. Just please yourself.
Thanks, why do you think assigning opus numbers to your own compositions is useless?
This got me thinking. Would any of today's tech-savvy composers want to assign QR codes to their compositions?