Someone had me use Hangouts for a press livestreaming thing a couple of weeks back. I was actually surprised at how the UI had improved since I last used it.

I agree that video conferencing is rather fragmented but I'm honestly not sure how much that has slowed adoption. People just don't want to use video in a lot of cases. Essentially all my internal calls are on a videoconferencing system and I doubt I turn on the webcam 25% of the time. (We do use screen sharing a fair bit though.)