There are so many 3rd party services that can and will do it better than anything SE could implement. Especially given that the ongoing DDoS on each of the datacenters would ALSO impact voice communication. Given that there are enough bandwidth issues for just gamedata packets, I would never want to add additional bloat going to/from SE's datacenters for voice when something like Discord works so much better. And for those who don't like Discord's approach, there's always Ventrillo, TeamSpeak, or Mumble servers people can run on their own. Or things like Google Hangouts, Skype, or FB Messenger if all the players know each other.
From what I heard about the built-in voicechat in WoW, it's garbage and rarely used. Perhaps that's changed since its release, but with the added benefits of literally any other service, there's no reason to expend development costs to force a half-working solution into FFXIV when Yoshi-P has already stated he doesn't think it should ever be required.
See also:
Literally this topic, but older.
https://blog.eu.playstation.com/2013...-realm-reborn/
Naoki Yoshida: We do not plan on offering official support for voice chat. To explain that decision, the idea of talking directly to other players with your own voice and making it a requirement to do so will not necessarily be a good thing for beginners and new players and many will see it as imposing pressure or causing them unnecessary stress.
I am personally a veteran online gamer so I completely understand the importance of voice chat but if we were to make it an officially supported feature then there is a chance that some players would start to demand that others use it just because it is an “official feature”.
Of course, we will not be prohibiting external voice chat via Skype etc, so individual player communities can still sort out their own preferred means of communication!