They are not asking for my email address. They want me to log in using a Facebook, Twitter, or Google account. That means that they potentially get access to my contacts and other personal data.

Yes, I know that I can review the permission. But I don't know what bug, exploits, permission changes, or mistakes will be made. I don't want to worry about that.

If they want an email address, I'll happily provide one. But I will not "log in" to their services.