I'm guessing they wanted G'raha to have natural progression. As in, it'd be too awkward for people spending an entire expansion and a half with G'raha as The Exarch to suddenly see him be his old energetic and investigative self.
The issue is that we're only given a glimpse of his Exarch self in Endwalker once. And that's when he steps up to tell the people of Radz to take shelter and calm their collective mammary glands.
Sure, he's always admired us. He's always wanted to have an adventure with us; he's had two of them. But he's not some puppy dog whose ears flare up at the mere mention of heroic figures. During the ARR raids, he struck me as someone who would have kept his cool, even if he was admiring the person. Now he's just an anime trope...
...just like making Y'shtola's younger self a magical girl...
It all just feels so unnecessary. He's such an interesting character who CAN offer a bit more if allowed, but his personality is just degraded and cliché. It's not sober.
I'll be honest, I fail to see his purpose. I understand his character and motivations, I just don't get his role in the group. Thancred is the big guy, Y'shtola is the smart Chick doubling as a power bomb, Urianger has become the smart guy Team Mom who teaches people to be kind and understanding of those they cannot comprehend at face value. Alisaie is our Lancer who Red Oni\Blue Oni's with her brother who's the team strategist and diplomat. Tataru is the Rowena and Krile is the older version of Alphinaud but with a more limited sphere of influence: she serves as liaison to some groups that the party can't just simply approach without rubbing anyone off. And we're the Hero, the designated party leader.
G'raha is... smart, yes. Investigative, but we already have 3 of those. He's strong, but not really a tank anymore, he's just combat-capable. What is he? Morality chain pet? Love interest\Emotional core? And what does he bring to the narrative? The experienced one who's seen Hell and can guide people through the darkest of times? Well, that's really only ever surfaced once since, if he's just gonna be like that all the time, then I worry for the people we meet.