I realize RStudio doesn't lack for ideas but its worth a shot 
One of my favorite features of vscode and Sublime Text is having a project/folder navigator on the side - I often end up using them concurrently with RStudio as I tend to find it easier to navigate through my scripts that way.
I would really like to see such a feature added in RStudio - may it could work similar to the way the document overview works on the sideline