Really, we sign up for new accounts for things all the time. I don't get the hate for having to sign up for one more, especially because like people said, you don't actually have to use the site for social networking if you don't want to.
But I think my biggest surprise at the reaction to the change is how everyone is complaining that Google is just doing this to get people to sign up for "a service nobody uses." If this gets people to use G+, then G+ will become useful and there'll be no reason anymore to complain about having to have signed up. And you can't get people to use G+ if you don't get them to sign up for it first. (I also suspect this is merely the first step toward complete G+ integration, so those who really don't like it may want to brace themselves.)
To go one step further, I don't even think G+ is that bad. Actually, I don't think it's bad at all. Obviously it's not perfect, but the bulk of the complaints I read are basically "it's crap" or "nobody uses it." I rarely if ever hear an actual criticism of something the site does wrong.
