Hello anonymous, not sure what is useless, and sorry for the bad experience if something is not working.
Would you mind being more specific on https://github.com/aaFn/Bookmark-search-plus-2/issues ?

Note that BSP2 is first a replacement for Bookmark Search Plus from the same author than Go Parent Folder. It does the same thing but runs from inside a sidebar, so that it can remain visible at the same time as your navigation pages.
Bookmarks Manager is a good add-on and is inside a pop up, which is a different philosophy.

I do not believe it is fair to compare both together, it is a question of taste, and tastes are never absolute.
What we all strive for is to be useful to others, so anything allowing to progress is much welcome.

Cheers, aaFn.