Another thought... There's a lot of historical ground to cover between the "Medieval Age" and the "Industrial Age" when it comes to tech levels. "Fantasy" tech levels don't always have to default to Medieval ones. They can be in any tech age the creator wants them to be in. I'm specifically thinking of the "Renaissance Age" and the technology that was invented during it. You've still got stuff like animal-driven transportation, but you also have stuff like the printing press being invented. And a whole bunch of other technological advances.
The Renaissance is also not too far off from Eorzea in terms of society either. You've got the Italian City-States, the rise of the Artisan class, mercenary groups for hire, a new wave of scholarly types coming in and developing new ideas... Eorzea probably has much more in common with the Renaissance Age then it does with either the Medieval Age or the Industrial Age.