I think a layer of fixed structure is one of the key factors for a good working Luhmann-style Zettelkasten - a form of a productive/creative constraint and a controll-layer against the endless possibilities of linking and tagging - and putting a note next to a accumulation of thematically related notes doesn't require a top-down hierarchie. Luhmann himself describes the growth of his Zettelkasten as a proccess of clumping, or as throwing something into a septic tank and waiting, which theme-clumps the future will bring. I think this is exactly what makes a Zettelkasten more exiting as lets say a Wiki-System with some kind of browser-history. To get that out of Joplin there has to be a structure-option which depicts that some notes are native to the core of a topic, whereas others are gradually more far away, new themes grow out of the themeline and some of them will build the seed for a new themepath in the future etc.
With the custom order feature this is basically already realizable, but still a bit unstable. So for me the development of that feature would be great:
- proper syncing custom order between devices
- Ability to sort notes in custom order on mobile
- ability to set specific logic of order for specific notebooks
- handy features like ' keep-current-notes-order-as-initial-custom-order '
- when a notebook is set to "custom order" new notes should go to the top, maybe even get marked (at the moment they seem to get moved to some random position!?)