I've been using GV since it was Grand Central... love it. I really hope it doesn't get killed, I'd happily pay $25-30/year just for what google voice adds over regular phone service. If they do kill it, I'll probably do a virtual PBX to get at least similar services I can control.
As an aside, I showed the email thing to a coworker pretty early on, it was pretty wild in the old days.
Related, Hangouts has started to be spammed. The spammers create a group hangout with a few dozen people, draw you into it, and then you see the welcome message. There's no blocking contacts from unknown people: rather, it seems like that was the business model of G+.
Granted, hangouts is almost gone now, but it demonstrates there's a way to spam almost anything and ruin it.
It happened a lot with AOL/AIM as well as Yahoo messenger, and even MSN messenger back in the day. To a large extent, I really miss those days... would love to see something like Yahoo messenger come back with voice chat rooms, maybe over WebRTC or similar.
Facebook Messenger is about all I use, and even then rarely... I use hangouts for mostly the occasional screen share or for SMS with my google voice acct (I don't even have my actual cell phone number memorized).
As an aside, I showed the email thing to a coworker pretty early on, it was pretty wild in the old days.