Personally, I'd be really cool with it. For dungeons probably overkill, maybe as a social aspect. For PvP I'd love it because I am a shotcaller and it would make it immensely easier for me (though I'd settle for text chat in setup time at least). Such a feature essentially exists in Overwatch, where you are free to join voice chat or not.

On the matters of toxicity as I bet some of you are going to type about it - it doesn't matter what game and what communication method, toxicity will always exist as long as we kneejerk react to each other and misinterpret what the others are saying. This however should not be the sole factor whether or not a voice chat should exist. Furthermore, the existence of a platform someone can be toxic on does not change the fact that being toxic is still against the TOS.

That said, the following issues would be difficult to address:
  • language barrier (though not gonna lie, would be a boon to learn a new language like Japanese)
  • in case of toxic behaviour, how would they be able to track it compared to chat logs?
  • given the technical infrastructure of the game, how qualitative would the voice codec be?

Discord also exists and is fairly dominant as the VOIP-Tool players use (or Teamspeak, for the tech hipsters). I also heard it now finally has Playstation integration, but feel free to correct me on that.

TL;DR: Controversial, but I'd love it if implemented well.