EDIT:
Most of this request is implemented. What is still missing is having customizable shortcuts for indenting and unindenting.
EDIT2: It would be nice if tab/shift tab could be used for these shortcuts.
Reorganizing lots of content in an efficient way is super important to me.
Shifting Up and Down
Re-prioritizing happens all the time.
Setting a custom keyboard shortcut like Ctrl-Shift-Up and Ctrl-Shift-Down should allow moving the line I’m editing Up or Down in the document. It should work the same for multi-line selections to shift up/down as a group.
Nesting In and Out
Since the markdown paradigm generally associates nesting with bullets, setting a custom keyboard shortcut like Ctrl-Shift-Right and Ctrl-Shift-Left should manipulate single lines and highlighted groups of lines respectively in the following manner:
- If a Shift-In is made on an un-nested line without bullets, add a bullet to line
- If Shift-In is made on a bulleted line, nest it inward 1 position
- If Shift-Out is made on a bulleted line, nest it outward 1 position
- If Shift-Out is made on an un-nested bulleted line, remove the bullet
Default should be bullet (or user setting otherwise) but if a precedent is set for any line regarding bullet vs. numbered list, preserve the line’s preference and contextual awareness for numbered lists.
If non-bulleted nesting is desired, a different keyboard shortcut could be used to simply tab lines (or groups of lines) in and out regardless of whether bullets exist and without adding or removing bullets.
If implemented, this feature would likely contribute to the single greatest joy for me in my Obsidian workflow. 
I just want to make a quick edit and mention that this feature should absolutely come with the option to choose your own key combination.