Agreed. This is the primary reason I don't use Google+. I haven't got the time or inclination to split people into groups or even figure out what those groups might be. I did try but found it a taxing process.

Automatically coming up with criteria to filter by is a great solution. I'd love if I could send a tweet just to my UK followers or to those who tweet about "Ruby" a lot. This is all easily solved by machines and doesn't require me to do anything by hand.