This update allows users to create accounts, and all the features that come with that. The goal is to eventually be able to link it to their twitch account, for those who want more advanced features and to be able to redeem channel points for custom TTS. In addition, Amazon Polly messages either are accounted for by IP address or username. You can still use this tool without logging in.
Note that account integration is done with Amazon Cognito, and is in compliance with the privacy policy. In short, your email address is only used to verify you as a user, and Amazon Cognito is the keeper of the data that I have access to. Your password is encrypted and NOT accessible.