Because you can automaticly upload all your blogposts on your Google+ profile.
Then people can go into their Google+ profile and add you into their circles.
Then - instead of jumping from blog to blog to see peoples updates - you can reach all your added friends from one place - and then surf the blogs further if you want to...
Better view of posts and pictures than on Facebook.
Because sometimes I get frustrated with Facebook! Some people use personal pages and some Fanpages which makes me confused - because these 2 kind of pages works differently...
I don't leave FB, because a lot is happening there. And so many participate.
But I hope Google+ and the blog-landscape will be more popular (again). I also find it less monstrously at Google+ - still lots of groups to join and people to get into cirle with ;)