It would be certainly nice to have this. There have been some related discussions recently about simplifying DICOM loading (less clicks, avoid the need of cleaning up the database). Maybe after this we can have a look this as a second step.
If you want to get started with it on your own then have a look at the logic in qSlicerDataDialog. It would be nice to modify the zip file to work similarly as general drag-and-drop. That way you could define custom handler, similar to the handler for DICOM data loading (see here).