Since we don't know for certain that there is a message conveyed by the Queen through her choice of jewels maybe we should not read too much into it. For instance on the subject of the York girls wearing the same tiara that Princess Eugenie wore at her wedding could indeed show support to the York princesses. But it could just as easily be a sign of quite the opposite.
And it is not the first time that the Queen has chosen to only wear the King's Family Order. And she is not unique in that respect as Queen Sonja only wears King Harald's portrait unlike her sister-in-law Princess Astrid, who wears the portraits of her grandfather and her father as well as her brother. Same with Queen Mary of Denmark.
As for the Bar brooch of Queen Victoria... it seems like the Queen has found out that it is rather useful to pin down the Sash of her Order, so I would not be surprised if we see this worn more often in the future.
It was a shame that the Princess of Wales was unable to attend, but her absence is understandable. But there were two other bejewelled ladies present; two of Queen Camilla's "companions" were present and they wore their most impressive tiaras.