As, one of Google’s main objective in making this tab is simply to free users from the burden of having to choose the resolution that suits both their video output at the time, as well as their bandwidth. The latter especially if they’re streaming directly from their mobile data.
That isn’t to say that the option disappears completely and that is why the advanced option is there on the list, for those among you who still want a wider berth when it comes to their resolution kicks.
As for when the feature will roll out is anyone’s guess at this stage. The app is still being labelled as “Beta” and Google hasn’t officially said when it plans on rolling it out to the masses.