I often need to use brushes from different categories (e.g. dedicated eraser brushes, markers, pens and pencils). I could add each of those brushes to one tag, but this would mean I have too many brushes to display and would either need to use tiny thumbnails or need to scroll the list.
This problem could be solved by adding a second brush docker, which I could set to a different tag. I could, for instance display my erasers there, so I could leave them out from other tags. That way, I could filter my brushes more precisely and find the ones I want without scrolling or changing tags often.
CSP users might be familiar with a “Quick access” docker, this request could give you that if you set the second docker to your favourite brush tag.