The registration barrier definitely played a role in our decision to not make having a Steemit account a requirement. While it gives you access to a lot of nice features provided by the Steem blockchain, we want to allow everyone to use the platform regardless of how they decide to sign up.
We believe that by showcasing the upvote based reward system (which is an excellent model for live streaming), we will bring attention to Steemit and convince some users to grab an account.
We are looking into ways to make the process of getting a Steemit account faster and more convenient in the future. (no ETA yet.)