I think it’s a decent idea to have a quick way to edit properties of objects in the content browser. The thing is, all details panels are attached to a specific editor (level editor, blueprint editor, etc) and are specialized for displaying the details of things in that editor. So the details panel in the level editor is specifically for editing placed actors. If you try to drag it out, it can’t be docked at the top level, because it is attached to the level editor. The content browser has no such attachment, it basically exists at the root level of a project.
So I don’t think it would make sense to use the level editor details for this - after all, it’s possible to have an actor in the level selected and simultaneously something selected in the content browser. They could though add a separate content details window, which was attached to the content browser and just showed the basic properties of anything selected, be it a blueprint, a material, static mesh or whatever.