Diana's ring was quite a generic design, I don't find it weird that Kate now wears it. I think she understands the significance of the ring to William and will treasure it for that reason.
Meghan's ring has no provenance, just the gems, so I suppose the design itself isn't sacrosanct. If I'm honest I think it's a strange thing to do but it seems consistent with her "out with the old, in with the new" reputation. Never mind that in her engagement interview she said it was "perfect", and that Harry designed it, and then he described in detail why he chose the different elements, including the yellow gold.
But if he doesn't mind, I shouldn't.