What distro are you on? Some don't install all available KIO workers and you'll have to install them yourself.
Is this something that is likely to improve going forward?
Like any FLOSS project, things tend to happen when programmers decide to solve a problem for themselves. If you don't the the skills to do this, you could always bring it up on the KDE forum under the "brainstorming" category, submit a feature request on the KDE bug tracker, or sponsor a developer to perform the work.