On Azem's role in the story

[Vyrerus]

Why are they part of this story?

Easy. It was the easiest way to give motivation to Emet-selch to want to personally talk to the player throughout the events of Shadowbringers. Rather than motivation for the player to like the Ancients, it's motive for the Ancient characters to like the player.

Think about the scene just before the Scions and the citizenry of Eulmore get The Ladder working. Emet-selch appears before you, and only you, to speak about Amaurot for the first time, while making facial ques that he's hopeful that he sparks a memory in the WoL. But of course, he doesn't.

Think ahead to when Elidibus first sends the WoL back in time to the Elpis facility. We're a shade, intangible. No one can hear us. Only Hythlodaeus and Hades can see us. And it's the fact that our soul resembles the current Azems that prompts Hythlodaeus to nag Hades into giving us form.

The Azem crystal, again, represents Hades's connection to Azem and us through them. It also had to be a functionally different ability from what Elidibus was using, because every person summoned in that way added to his power.

So, you tell me, what better way would there be to make the Ascians / Ancients want to interact with the player in a friendly way? (As an aside, Venat interacts with the WoL differently because she doesn't seem to have the special sight Hades and Hyth have. She smells her own magic, and is drawn to us as a message from herself. It's a tad conceited, but I digress)

[Cleretic]

So, you tell me, what better way would there be to make the Ascians / Ancients want to interact with the player in a friendly way? (As an aside, Venat interacts with the WoL differently because she doesn't seem to have the special sight Hades and Hyth have. She smells her own magic, and is drawn to us as a message from herself. It's a tad conceited, but I digress)

Frankly, I don't think they need it.

Hythlodaeus is a frustratingly friendly and helpful guy who probably would've said and done exactly the same things anyway. Granted, we have absolutely zero context for how Hyth deals with strangers thanks to him only knowing us as someone he recognizes... but since we've never seen him around strangers anyway, who's to say that's not his normal demeanor anyway?
Venat confirmably doesn't need it, she barrelled right past that plot hook to instead grab onto a much more personally interesting one (and frankly, one that probably would've worked for Emet and Hyth if they really needed it).
And Emet... well, I would never once consider our interactions with Emet friendly, he never once got warmer than 'begrudging tolerance' with us.

But further on Emet, I don't think he needs Azem as motivation either, he's already got plenty. Emet allegedly cares about his people, and wants us to realize that too. He also knows that the Echo is a sign of someone whose soul goes back to Amaurot (even if we wouldn't learn that for another couple patches), so that's his reason for nostalgizing to us; he knows that we, unlike everyone else, actually does have some capacity to remember that. He also doesn't need Azem as a personal connection to motivate him; mostly that's because he never discusses something like that, but even if he did, Hythlodaeus is up there in Zodiark; that's all the personal motivation he needs.

So yeah, I don't really think this squares either. And even if it did... I mean, surely they could've written that without making the person he recognizes us as an ex-member of the Convocation, and they definitely could've not brought them in for Pandaemonium.

[Vyrerus]

Frankly, I don't think they need it.

I'm sorry, but there's no real way to replace the line, "It's right here. A bit thin in the aether, but there's no mistaking it -- the color of its soul is almost identical to Azem's."

The entire reason he stops at all is because it's a soul almost identical to someone he knows. Either way, we're getting on the bus because of a personal ancient acquaintance. A friendship no matter how you slice it with someone important.

Even if that were the first instance of our Ancient identity coming to bear, as in if Hyth said something like, "It's almost identical to my friend Rando Ancient #42." Then we'd start learning about Randy #42, wondering about them, and wondering why they weren't on the Convocation or in some other important office etc.

I also don't think your take on Emet's personal motives really holds well, either. If he cared that much about any old soul, then why wouldn't he want to raise as many of them as possible as soon as possible to being lesser Ascians? Imo, you are underestimating/devaluing the idea of personal connection too much. Yet, even if he did, do you imagine yourself liking the set piece any more than you already don't? The intangible Elpis scene would then play out with Hades wanting to stop and be kind to a stranger, over Hyth wanting that.

It's kind of what others have already said on page 1. They chose to go with what would likely be a popular hook, since ties to the Ancients' world were gonna happen even without it. And they also chose to go with that hook being for character motivation outside the player's. It's the plot device they chose to use.

It's kind of like asking, "Why did you decide to play that piece of music on a flute? You know, it would sound a bit better played on a clarinet."