But I only have those conversations with a small number of people, so I can't argue against Google's usage conclusions.
I use and enjoy G+ more than Facebook, and I have no interest in Twitter. I probably just won't have those conversations anymore =\
But I'm gonna miss it. I haven't been too active the last few months so I guess I might be to blame too (but then again I've not been active anywhere else either lately except here).
Where else do you go to meet people who share interests in a more general sense? HN doesn't care about photography. Twitter doesn't allow me to chose to see someones photos but not their crazy posts about politics. Facebook... well, don't even mention it. It's less than a week since last time they let hackers access theirs users accounts, and even if they had a perfect security record wrt hacking, it seems they just can't stand the temptation to abuse data: change settings, do experiments on users to make them depressed, abuse 2-fator phone numbers for spamming, ask people to upload nudes - many of us couldn't make this up even if we tried..!
I use their mail, as a backup, their maps, and search engine. But I'd think long and hard before I developed against one of their services, or came to rely upon any future-project they released.
The new GMail is also helping me with that.