Mainly for Solo Queue and Parties with LFG.
It can be optional to join voice chat, but I think it would help game play and cooperation between people which randomly use Solo Queue or LFG tools. It would help communication and speed up dungeon runs. It would also be pretty cool to see how people who have never met each other would cooperate in Solo Queue and dungeons
This has worked in several other games, and although outside devices such as team speak would still be more common, it’s still a good idea in my opinion.
I am also suggesting that the voice chat be optional as mentioned before so if people are kinda busy or listening to music or many other excuses, they can still opt out.