It would be great if you could load a Revit family from one project to another, similar to how you can duplicate layers in Photoshop from one open file to another. It would skip the extra step of having to open the family file from the second project and then load it into the new project. Alternatively, it could work similarly to how you can load views from other projects where you can load from a list of families in your new project. This is something that could be helpful if you don't know the route file location of your family.