That limitation makes sense and technically your work around sounds pretty good, but the point of the change is that the workflow slows down when you have to move to a different section of the editor and adding a new details panel would only further crowd the editor, which would likely greatly reduce the benefits of the proposed change. And while I agree that theoretically allowing you to select something in the editor blurs the purpose of the details panel in the level editor you can already see a successful implementation of this general purpose details editor in the Unity engine.
So perhaps a good hybrid approach would be that you could set a level-editor-details-panel and a content-details-panel in the same location (two tabs sitting next to each other):
Then in your editor options you could have the option to “Change Focus on Selection” which would allow you to have the editor change the focus from the level-details panel to the content-details panel when you make a selection in either the content browser or the level editor:
(Yes this is just a second level-details panel, the purpose being illustrated is that you could have the two tabs swap when stacked together like in the images)
So for example if you are working in the scene the level-details panel is available and then if you decide you need to edit an asset you click the asset in the content browser and the content-details panel will be brought to focus (set it to be focused when the tabs are part of the same frame) and then once you’ve made your changes you can select something in the scene and it will swap you back to utilizing the level-details panel.