The aft balconies are about the only way to get a balcony on E class unless you are in a suite. They are booked up early and are more expensive. Sure they have the obscured porthole balconies, but I do not count those as they are obscured. And IVs are not balconies.
To be honest I don't understand the clamor for E class (unless in a suite) especially when sailing to a scenic destination.