It is my understanding that the other 'guardians' were unique under the Daisy scenario. Due to the nature of the Guardian being a semi-last minute re-write to an integral character, they likely did not have sufficient time to re-do a unique guardian for every origin (bringing VA actors back in, re-recording an entirely new script, etc), so it's a what-you-see-is-what-you-get sort of scenario.
On my a personal level, I think they should have kept Daisy but re-wrote he/she to be more subtle, but that still begs the question, that any re-write of the original or the change to the Guardian would still require time and resources, which I'm guessing they didn't have.
