Man, I'm glad to read some anti-social login stuff, as I personally do not like everyone depending on FB. I've read articles on tech crunch which say to ONLY have facebook logins for MVP, which made me cringe.

However, the key thing to realize here is that 3% of mailchimp's users use the social login buttons. That doesn't translate to 3% of your users. One app I work on is a social app for music fans. Most of our users hit the facebook button. It's also mobile, so that might have something to do with it as well (people might not want to type on mobile devices as much)

Takeaway: you need your own stats.