Editable Brushes - Be able to change the art of the brush not just the settings.
When you make a brush using selected art currently you can only edit parameters about that brush. You cannot make edits to the art that is at the core of the brush. It would be great if you could edit that art. Like how you can edit the objects that make up a symbol.
Right now the only solution is to just make a new brush if you need to change the art.