My thoughts exactly. Since adopting Slack, the only time we use anything else is Hangouts for videoconferencing. Even using the attached chat in the hangout feels clunkier than using Slack chat during a videoconference.

When you really feel it is when Slack goes down and you have to go back to using something else. There are just so many little details in the presentation that make a text chat in Slack feel right. Adding videoconferencing to their platform is the logical next step.

In an ideal world they'll find a way to improve on video chat similarly! I'd be plenty happy though with an experience comparable to hangouts, but without leaving Slack.