It would be a significant improvement if we could have public login's (either facebook, twitter, arcgisonline or google...etc) to allow for public commenting.
It would be a determining factor of whether or not webscenes are used as part of public engagement, at least at the municipal planning level.
Perhaps there could be a another way to 'administer' commenting on webscenes that would make it more advantageous for public engagement/feedback.
Mike