Because sometimes allegories are worse than a good, realistic portait. I’ve put this example before, centuries ago. Everyone remembers the portrait of Charles IV of Spain and his family by Goya:
Entire books have been written about this particular portrait and how Goya had supposedly mocked the sitters (when it’s clear from the correspondence that they were pleased about the result). And then, when a contemporary painter tries to give this charming group the beautify treatment of an allegory, this happens:
This one is by Vicente de Portaña López Portaña, commemorating the royal family’s visit to the University of Valencia in 1802. An example of how sometimes allegory fails. That, and that Goya was a genius but that’s another story I guess.