What's the point with that quite lackluster story in Endwalker?

[Rosenstrauch]

Alternatively, they may have been able to present Elpis as an untouched relic of the Ancient world (Which is what almost everyone seemed to think it was when it was initially shown in pre-release material) to avoid the time travel entirely, though it doubtless would've made for a less intriguing zone if we were learning of the past strictly through records and perhaps Echo visions.

Something really crazy they could've done is build on the memory interaction shown in Bozja. Have the player go to Elpis in the present day, only to discover that little remains other than ruins. Then use the memory crystal things, the Echo, and the location's memories to "travel" to Elpis in the past, assuming the role of an important character there. We could learn about what happened in the past through several dives—let's say one for each of the big islands—and culminate them in exploring the ruins/past memories of the dungeon there.

Doing it like that could completely avoid the time travel/closed loop plot. We'd lose the unique trusts, probably. And I think Venat would still need to lose her memories from that point on, and only regain them after sundering the world and placing herself in the aetherial sea. By that point it would genuinely be too late to act on them, since she'd already squandered her best chance to defeat Meteion, and is now tied up in maintaining Zodiark's prison.

EDIT: As an aside, since we learn about Elpis from Elidibus and since Elidibus's sacrifice was solely for the sake of the time travel plot, he would still be alive in this case. We could've extracted him from the tower. Found a way to have him join us. Whether as a permanent fixture in the plot or delaying his sacrifice until, say, the Aitiascope or the journey to Ultima Thule.

I think that would have made up for losing some of what I liked about Elpis—the side quests, and the friendly interactions with the core Ancients.