No need to do that. I personally am happy with everything in one folder but don’t see the need to add the path “…/assets/link_to_file.png” in the link. Just use [[link_to_file.png]]. We don’t have to link to “…/pages/link_to_page.md” to link to a page … so why would we need to do that for assets. It is inconsistant. And it is highly unlikely you have the same names (page and file) as files always have extensions.
That would be the default behaviour. The people who would like to have multiple folders are probably the ones you do not have to explain the unix syntax to go up or down in folder structure. But / should be assets (or configurable).
Logseq could easily show a folder list of existing folders in the assets folder if a file is dropped in logseq to make the user choose where to store his file. If no folders are found (default) it is just added to assets.