Enkidoh, your lore is outdated. HW includes a number of male Miqo'te in major roles, and even in 2.0 there was usually a token one (now two, post HW) hanging around the Scions' base, if only to say to male Miqo'te PCs, "It's not that odd for you to be here." So if A'aba and V'mah can stay part of the same organization for an extended period of time, there's really no reason one can't be a focal character in said organization.
Grayve, you're right, and wrong also. He actually had some quite revealing extra dialogue if you talked to him between quest checkpoints (or in the three-month stretches where he was just standing around Saint Coinach's). It was meant as foreshadowing, I think, but it only served to put his actions in a context that didn't justify the finale. I think each leg of the series was meant to be as long as that first long slog to collect the four fangs, but they ended up cutting everything down for some excuse or other, meaning the character they had meant to take charge got sidelined by the Cid and Nero show and then promptly discarded. This is probably why Cid now spends most of Alexander occupied offscreen.
Mildly Ranty Addendum:
I don't really want to debate this anymore. We all have our opinions, and we all know we're right, so it's not going anywhere. I just think that a lot of CT simply doesn't make sense from a stand-alone narrative perspective. If the story can't have any lingering effect, why give a character potentially lore-breaking knowledge that can't be allowed to exist in the outside world? If, in spite of that, his only actual purpose is to introduce Doga and Unei, and then exit by repeating the same emotional beats, why introduce him to begin with? Just introduce Doga and Unei off the bat, have Doga stay behind and Unei seal herself in the tower to the protestations of Nero. And why have him interact with Nero at all, if it's just for one scene that in all likelihood will never come up again? It's a waste of running time and doesn't actually develop either of them.
So mostly I feel sorry for G'raha for being a completely superfluous existence. It's a shitty way to use a character, and I'd feel the same for anyone treated like that. That it happened when male Miqo'te were at a premium is just an extra twist of the knife, really.