I don't think "unloading" modules will ever be a thing. While
ResourceLoader could be made to keep track of modules' CSS to be able to
remove it, we can't "unload" JavaScript modules at all (because their code
has already executed), so I'm not sure if we'd want to add such special
case.
If you want a slightly less horrible hack than you do now – you could
generate an appropriate load.php URL yourself (with &only=styles) and add
that in a <link> tag to the page, much like we did back in the old days
with importStylesheetURI(). ResourceLoader won't even know the module is
loaded. And this way, you can remove the <link> tag later without messing
with ResourceLoader's internals.
--
Matma Rex