I interviewed at Google a while back for an SRE position working with the Hangouts team. My first interview was in another office and the audio in Hangouts session would not start. We ending up having to move on to the next interview. I'm not surprised even Google employees don't use it.
Some of this is consumer vs. enterprise tension, though. Emoji demo really well on an initial product tour; reliability is one of those key features that's really hard to get people excited about, but which people hate to find lacking.