Yes, much-to-be-desired, IMO.

Here is a visual example (created in iGigBook):

Click image for larger version.  Name: Four - Marked Up 01b.jpg  Views: 11  Size: 45.1 KB  ID: 694

It would be superb to be able to do this directly in iRP!

Also, see the under-measure notes here as well. These would have many potential uses. The example shows notation of semi-tone key motion and scale selection.