When using the Dashboard Theme, the widget label in Web AppBuilder (ArcGIS Online) should be hidden from the final product - or at least have the option to be hidden. In edit mode its ok... The label doesn't really add any value for the most part and it takes up a lot of space. It cannot be left blank (not that this would necessarily work anyway). In the example below, 1/3 of the space is taken up by the widget label that the audience doesn't use or need to see.
This top section also contains the maximize option (top right). Nearly all of the time i don't require this, so I would be happy to have an option to turn on/off the widget header section as a whole.