Final Fantasy XIV doesn't actually have that good of a story

[Herebedragons]

It's funny you talk about how "normal people" speak when referring to the writing in this game. I don't know where you are from but I have never heard anyone say things like " 'Tis no ordinary woman who can face a primal and emerge the victor! " and "Mayhap a brief summary of the situation would help clarify your thoughts on the matter" or how about "And all not afield will aid the fight from afar"

The writing is used to make the events and things said seem more sophisticated and grand. Here, I can do it too if you really like:

"Please go to the store to get some milk"
can be turned into:
"If you are so willing, go henceforth to the store and procure me some milk"

Both say the exact same thing. Which one was easier to read and understand? Which one sounds more like how people actually speak? You think that just because a character uses long words that it is more adult?

As for the characters, if they are so memorable, give me some defining character traits of say, Minfillia or Yshtola or Alphinaud. For all the time we have "interacted" with them, we know hardly anything about them. I know more about Sylvie from the Conjurer storyline than any of the Scions, despite having done a fraction of the quests with her.

I'm not sure why people are so hung up on the way some characters speak. The use of colloquial, common or elevated speech in itself tells you something about a character. For example, let's compare Arenvald and Urianger. The former is an orphan who never received an education and resorted to petty crimes to survive, the latter is a Sharlayan Archon who was taught by Louisoix himself. Their speech patterns reflect that. It's not about being easy to understand, it's about character and world building.

As for characters being memorable, there's a part of subjective in that too. For some people it sticks, for others it doesn't. I agree with you about Minfilia, but not Y'shtola and Alphinaud. Someone else will think differently still.

Also, do keep in mind that the MSQ isn't the only content that gives information on the background of major characters: the SMN job quests, the ALC job quests, off the top of my head.