I personally consider hierarchies to be extremely important, if an item can appear in multiple parts of the tree. If a system would force a unique hierarchical classification of each item, and the item would only be visible at a leaf node, it would not be beneficial.
What I would like to see (some of this already works with nested tags):
- Tags get a place in the hierarchy, e.g. “Historical Complexes” will be marked as part of “Non-Fiction”, “Non-Fiction” will be a part of “Writing Projects”
- The relationship for tags and hierarchy positions has to be 1:n, i.e. each tag can have multiple parents or none. E.g. “Historical Complexes” can also have a 2nd parent “History”, which is a child of “General Interest”
- Entry of tags should have some form of smart autocomplete, i.e. when I enter “History”, it suggests “Historical Complexes”
- All items also appear under their parent categories, so when I click on “Writing Projects”, it will link to all pages under this category. The reason for this is that one should not have to go to a folder at the bottom of a hierarchy to find an item
As a generalization of the tag system, Logseq could implement nested searches. This would allow to place all pages (or blocks) that match a certain search into a folder hierarchy (e.g. “Historical Complexes” in the “Non-Fiction” search folder, which could also contain other subfolders. This would be an improved version of Zotero’s search folders, which don’t allow hierarchies. Such an approach is more powerful (e.g. one can have search folders that require multiple tags #history AND #fiction), but also slower.