Google+ is a social media platform, ie. Google's attempt to compete with Facebook. They've been increasingly aggressive promoting it, to the point where a Google account and a Google+ account is one and the same. It's quite annoying.
Probably, but let's be fair that the same could be said for MSFT and their ubiquitous live account. You certainly don't have to have one to use their products, but it is annoying if you don't.
I wish the companies would standardize on some kind of federation technique so the could compete on the merits of their products, not the stickiness and annoyance of setting up another account.