Kind of a silly question, but how do you not go snowblind playing as anything within the HRE? It's painful. And even your vassals are not delineated on the map.
Combined with the fact that the HRE is, by default (I know that you can change it), an ugly gray color, and you have all the motivation you need to do your best to ensure that the empire dies a painful death in all your games.
The Direct Vassals view, while fine for what it is, could really use an extension, allowing players to choose whether they want to see Direct Vassals only, or all vassals.