Your assumptions seem pretty fair to me. We have to do a better job of teaching people that the topbar contains grain-related functionality -- specifically, fun

Your assumptions seem pretty fair to me. We have to do a better job of teaching people that the topbar contains grain-related functionality -- specifically, functionality that is mediated by Sandstorm, like access control. FWIW, the first version of Sandstorm let you copy/paste the URL from the address bar, and I'm definitely a fan of that model. But, a lot of people are uncomfortable with that. It "feels" insecure. So we're trying to find a happy middle ground, where the people who like URL sharing can use it, and those that don't can avoid it. It will take some experimentation to get right.