But Google doesn't segment their chat products based on target market, they segment it based on business unit. Google is just really unafraid of competing with Google in the marketplace, apparently.
OK, so here is consumer case: weekly video call to parents, who live separately. Duo? 1-on-1. Hangouts Meet? enterprise. Original Hangouts? Who knows how long it will be here, but hey, Google Voice suddenly got updated after 5 years of neglect. Doesn't get any more clear than this.
I think it is an uncommon use case, but I wouldn't say exotic. On the other hand, which of the latest services support it? WhatsApp doesn't, FaceTime doesn't (although they're rumored to soon). So I'd guess it isn't common enough to be launched in the initial versions.
On your second point, yes, you're segmenting by use case, I was segmenting by target customer.
* Video-conferencing & meeting: Hangouts Meet
* Direct messaging & team communication: Hangouts Chat
Target market: consumer
* Video & audio calling: Duo
* Text messaging: Allo
You could even put it in a 2x2, doesn't get any more clear than this.