You'd think the entire thing about the Lighthouse, the sunken city and the Orbonne Monastery (Alongside Fran's mere existence) would have been enough to sate XI fans.

Not to mention Mustadio, the Thunder God, ULTIMA HERSELF and several other noteworthy players in that particular adventure.

While it's never really a 'bad' thing to expand and flesh the world out more. One has to remember and realize that every Final Fantasy takes place at different times and (more often than not) different timelines / planets all-together. The nods to other games in the series are just meant to be nods or tongue-on-cheek references.

They could easily just not have done it and people would still do the 24-mans. Remember that, if they make a 24-man about a certain niche or franchise (A la the Nier raids we're getting this expansion.) then it's taking the place of something that could be original and unique to XIV's universe.

XIV's Eorzea is amazing by it's own right. It shouldn't need to pilfer from other times and games to prove that and instead, shine by its own strengths.