This is missed by many users including myself
I would go even further and suggest that RM lacks the ability to view and edit all manner of data items that are linked to other data items. Why not be in the Sources list and be able to edit the citations associated with those sources. Why not be in the citations list (well, there really isn't one in the sense I'm thinking of it) and be able to see and edit those people and events associated with those citations? Why not be in the media list and be able to edit the items to which the media is linked? Etc.
RM does a better job of "seeing" these linked items than in editing the, but even the "seeing" is pretty problematic and limited in many cases. Most of the time the best you can do is make a report and store it in a file an then go back and forth between that report in the file on the one hand and the RM screens on the other hand. I think the trick in any such support is keeping the screens comprehensible, especially to new RM users.