works as intended and how it should be? because you're grabbing a specific version from the tfs on a specific path.
this would be the same, when you're doing it e.g. in visual studio, when you navigate to a folder and say get latest or specific version, all files from that version will be downloaded.
if you really only want to download the last changed files, I think you need to put in some more work, like checking the latest changeset and download it file by file