What XIV can take from XI to make it better

[Zantetsuken]

Magitek from FFVI.
Crystal Tower from FFIII.
Golden Saucer type location from FFVII/FFXIII-2.
Typhoon from VI/VIII/XIII-2.
Fenrir from VI/IX/XI
Amon from FFIII.
Chocobo Raising/Racing from FFVII, IX and XI.

XIV is a fanservice game, they already stepped into the realm of borrowing ideas and designs from a previous FF game.

Fixed some of those.

In reality, the only fan-service elements that are unique imports to FFXIV are the magitek armor (which is an exact replication of the FFVI design.. for better or worse) and the Crystal Tower, and Amon, who are both generic enough that they can seamlessly fit into the lore of this world.

EDIT, I forgot about Materia... which is certainly a wholesale import from FFVII.

Overall, I'm happy with the measured amount of fan-service. FFXIV is still its own game, and as long as the devs don't get too carried away in the future, it should be ok.