The integration. Before, anyone could easily find a hangout via the hangouts section, I owe my entire career now to people I met that just hopped into random hangouts via finding them via G+'s Hangout section. That was thanks to integration. Now that the full integration is gone, hell even the #hangoutpost
hashtag has been scrapped, no one looks for them anymore. You invite to the people you already have and that already know you. You don't get random, meaningful interaction anymore.
Also, you can invite via circles anymore, which is another piece of integration that is sorely missed.
Here, check this post from just yesterday and all the people lamenting the fact that they are gone.https://plus.google.com/u/0/+WillHiggins/posts/76MXA8eQ9gL
This place has never been a ghost town, and it never will be, but now all it is is another stream where people shit post stuff they find elsewhere on the internet without giving credit(myself included), they post their photography or their latest #SEO
blogpost. #Pixelpushing #hashiestoftags
It's stupid. Hangouts integration made this place fun.
If you actually care to hear more, I can tag in quite a few people that would love to explain their thoughts behind why G+ is just becoming another stream.
For me, as I said above, I owe my whole career to G+ and Public hangouts. I learned linux, networking and how to refine my programming, all through people that I met from beta and beyond. Now all I have is a subset of people that like to still hangout, and even that is dwindling. I can't make organic, natural friends in a stream the way I can through a video chat.