Now here lies a field where Canonical can make a visible, tangible difference... I'd say the best solution is a client with a separated front- and backend so my current vote goes to mpd. The available frontends for mpd are OK but they probably do not live up to the expectations of those looking for the bling and featuritis associated with this type of software. What mpd has got right is more important though:

a) speed, b) stability and c) interoperability. Here at home music (local files, internet radio stations or files shared by networked machines) is streamed from the 'server under the stairs (a BP6 with 2 x 466 MHz Celeron processors...)' to whatever machine on the network I happen to work on using pulseaudio (but not rtp as that crashes dd-wrt-based routers...), I can change tunes using anything from a simple command line client to a full-fledged, album-art-and-lyrics-including player application (gmpc) or even my phone. Of course you can also run the daemon and client on the same machine to get something similar to the more traditional media players. The opposite is usually not the case.

So IMnsHO mpd already fits the bill but if more bling & features are wanted Canonical could put some people on building a client which provides those. There are many projects which something like this can be based on... just take the good features from all of them (eg. Rhythmbox's search) and combine them in something lightweight, stable and snappy.