I'm not sure how Blizzard's new integrated B.net chat is going, but when they originally introduced voice chat to WoW back in like 2007, people pretty much just didn't use it ever, despite the fact that back then the popular choices were all paid. Now that Discord is being a thing, what benefit is it to me for them to develop an integrated chat function, especially because it just creates pressure to join voice chat with obnoxious randoms? Discord is free, sufficiently high quality, and practically ubiquitous already.