About the blue blood
What would have happened if Ayato had never met the girl in the yellow dress?
How would the plan have gone then. Would there have been a Tokyo Jupiter?
SPOILER WARNING
Ayato might then very well have tuned the world to one where the Mu dominated or where the red-blooded might even be extinct. Maya would be more "evil" too I think.
PS: And yes, there would still be a Tokyo Jupiter.