I've seen both sides of the arguments by now...

1-If they add VC then most people would demand everyone to use VC.

Solution: Even if it was mandatory, all you need to do is mute your microphone during a raid. All you require to do is listen to instructions, other wise you'd be the tank asking people to VC.

2-Not adding it doesn't make it mandatory for everyone.

The downside: Still a lot of groups demand it even if it's not mandatory, so at this point in time it's almost mandatory.

Conclusion: It doesn't hurt to have more options available, this idea that "This won't work" is just negative talk. We all adapt to whatever changes come, we can adapt to this too.