We need to keep in mind that we are the old generation: We all have more than 10 years Internet experience and we know how many times Facebook has betrayed us.
Now we should ask the younger generation and people with non-IT jobs what they think about logging in through a social network. Perhaps it's just another noise like managing URLs and Adobe updates.
Indeed, for them it's probably just a click, they already have no expectation of privacy on the Web. I'd really like to see numbers for various registration methods (where several are available), as well as age distribution for each.
I think we should be asking the older generation why the proposed SSO/Digital Identity solutions from a decade ago never got traction. OAuth is the only thing from back then that got anywhere, and it's been stripped of its identity management components and reduced to single sign-on.
Now we should ask the younger generation and people with non-IT jobs what they think about logging in through a social network. Perhaps it's just another noise like managing URLs and Adobe updates.