It would be nice if you could select the devices in the dynamic folders so that the communication objects appear in the right window. This helps, for example, if you want to filter the comm. objects of a large number of identical devices in order to quickly connect them to a GA. Of course, you can select all devices and than set the Filter you need.
But there would be many other possibilities if you could open the folders. In my oppinion, that's when they really make sense.