I think of it as a useful feature searching for specific game modes that the site does not list and also keywords for tile-set themes, since the current search method only allows you to search for those in the actual title and description which can be a highly inaccurate method.

I don't consider it a feature worth expanding. Since it requires users to tag the files themselves, it means tagging every file to be included in the search. As an actual search method it would only limit the results to recent or popular files and in comparison to the rating system, it's not based on fair reviews so level makers aren’t entirely rewarded for their efforts in the file archive. It would also be possible next to impossible tagging all files properly because J2Online is too big and too old for such a small community as the current to manage such an enormous project.

In my eyes, this feature just seems like something that the site administrators did for fun, which allows the more active users to influence the site a little more and to play around.