Personally, I don't think putting forth effort into missing codec
installation makes much sense. Since this feature isn't working well,
we might as well just disable it. If you have to enable rpmfusion to
get the missing codec workflow to work, well, users who are smart
enough to do that can just install the codecs they want anyway. It's
better to ensure that we install whatever important codecs we can by
default.
I think totem is still useful though. MP4 and AAC are both coming soon,
right, and it's expected to be good enough to play most MP4 files,
including web videos? Why do you say they are "rather incomplete"? Even
without MP4, it's still helpful to be capable of playing WebM, e.g.
gnome-shell screencasts.
Michael