I second this request, it's a feature I used to use a lot too!
I think it could by synced to something like CMD + DOWN and CMD + UP. I miss having expand and collapse mapped to two different arrow keys. When expand/collapse are mapped to two different arrow keys, you can basically do all your moving, sorting, zooming, expanding and collapsing all from the four arrow keys. Your right hand stays right on the arrow keys which are fast and intuitive to use (just tap the direction you want to go) and then your left hand holds the correct modifier key based on which one you want to do.
An example keyboard setup can be:
Hold CTRL and the arrow keys become:
UP = Collapse (level by level)
Down = Expand (level by level)
Left = Zoom Out
Right = Zoom In
So basically by holding CTRL your four arrow keys become an intuitive "view change" mode, where each arrow key corresponds to shifting the view in that "direction".
Hold CTRL + SHIFT and the arrow keys become:
UP = Move the node up
DOWN = Move the node down
Left = Un-indent the node (e.g. move it left)
Right = Indent the node (e.g. move it right)
Like the above one this set of shortcuts is really intuitive. Hold the modifiers and use the arrows to move the node exactly in the direction you want it to go.