In that way, video calling feels old-school before it's ever even cool.
Even if everyone decides to get down with video calling, Google needs to get tons of people to download the app if it is to become part of the world's messaging lexicon.
Facebook Messenger allows group calls already, but the same functionality could prove much more popular on Whats App, as the quality of calls made through it tends to be much better.
However, it could also prove extremely annoying, especially if you're busy while other people in the group chat are free, bored and looking to cause mischief.
On the other hand, if someone rubs you the wrong way you can jump immediately to the next conversation.