Since each account is currently linked to one email, it's not possible (or very difficult) for users to launch small shared workspaces to use with different groups of users. They will all be linked to the primary account's email, which will usually be linked to a single project or job. I really like the idea of private workspaces but without the ability to login with a different email on each workspace you make all of the dependent.
I understand the current design limits accounts to have only a single email, I think this is where this would have to start.