I would love to be able to drag from an existing node to create a new link - either to another node or to a new node, which would create a new file/note. This would be similar to TheBrain, which is a mostly graphical approach to notetaking/knowledge management.
The issue with this is where to put the link. It seems to me that a YAML field such as "links: ", which lists all the links that are contained in the current file, would be an appropriate solution to this problem. You could then just create “non-text”/relational links between the files - either from dragging on the graph or right in the note.
I have also created another feature request for link attribute YAML fields, which could have all sorts of interesting uses.