MSQ

[MariaArvana]

You are assuming it wasnt the plan all along, and that this entire arc wasnt fleshed out a long time ago.

It wasn't. Early FF14 was a lot of touch and go, as this answer for question #9 from a lore Q&A mentioned in this thread: https://forum.square-enix.com/ffxiv/...-transcript%29

Naoki Yoshida:
So if we take this example to refer FF XIV as a tv drama series we kind of apply the first season of FFXIV as ARR (A Realm Reborn).
If the result is not good then the second season, Heavensward, could have been the end of the journey.

We had these overall details though we didn't elaborate those but when we started developing on A Realm Reborn and saw that the rhythm is there and it is looking great we expanded upon to decide on settings around the Ascians.
For those who are handling the main scenario being Oda and Ishikawa - especially Oda they going back to the pages and dialogue and fact log with a thoroughly research and try to adapt those facts.

And after that they add more into it but without creating too many contradictions with the ones that created the facts beforehand and they improvise the new facts so everything fts up nicely. They are skilled to weave out the great story and the lore which is extraordinary.

Basically, they were unsure if ARR & Heavensward was going to be successful or not, so didn't worry about long-term story planning in 2.0 due to the prospect that FF14 might have failed around that point. It wasn't until after HW's success they started planning more long-term. This can also be easily seen in how they retroactively made Crystal Tower required for MSQ; if they had known it'd be mandatory for MSQ way down the line, they would have 100% added it in as mandatory back in the 2.x series.