The biggest improvement for me is @CalebJohn's InlineTodo plugin. I realize this came out in 2022, but I only discovered it in 2023. It finally gave me an effective way to use Joplin as a todo manager - there's lots more that can be done to refine things on this front (some of which are probably not possible with the current API), but it was a game changer for me. I think a lot of people don't use Joplin as a todo manager, or have a relatively high maintenance manual approach to make it work as a todo manager. I think a note app is a natural place from which to manage todo's, so I hope we continue to see improvements in this regard.
I think the biggest pain point for the average user is probably the mobile app in terms of sync and editing. I don't need to use mobile that much, but every time I do, I am reminded of how much I preferred Evernote's mobile app (while the opposite is true of the desktop apps - Joplin + plugins blows away EN desktop). Background sync and easier editing would probably be huge for the average user.
Great app overall, and gets better every year.