I remember at the end of college and right after (I graduated in 2008), many of my close friends were on GReader and we would share and communicate directly through it about interesting things we were reading. It was an awesome way to interact, and nothing has replaced it for my group and me. Google's implicit (although I could be reading their intentions incorrectly) strategy of trying to route that interaction through GPlus did not work for us. Too much overhead and it never materialized. Now we just use email, which is fine. So on the whole it's a type of social interaction that has simply gone. It's a shame, because I think that Google could have done something with this. But they are just one company and the number of innovative things they're doing is really impressive.

Maybe this will clear the way for a competitor that replaces the social interaction component and innovates on it. I'd be a user for sure.