Being able to log in via an Amazon account
It would be nice to be able to log in via the connected Amazon account. Another thing would also be to automatically change the twitch e-mail when the Amazon one gets changed/updated.
This is a great idea, and it's shocking to me that it's not available.
This concept is known as Federated Authentication. This would have the bonus side-effect of allowing the use of Amazon's security settings to protect an account, such as OATH TOTP.