Why now WMA

WMA is a proprietary format controlled by Microsoft. Very few platforms
support it, although it is becoming increasingly popular on standalone
DVD players etc., and some applications for *BSD/Linux will support it
by using Windows binaries. AFAIK there are no alternative WMA decoders
implemented by anyone.

MP3 is a proprietary format based on open standards that is now
supported by damn near everything thanks to the availability of numerous
encoders and players for the fomat.

Another option is Vorbis. A completely open format that anyone can
implement. Oddly enough this isn't widely used.

I am us VBR MP3 files for my own sounds.
Tools like Exact Audio Copy will rename files based on CDDB information as well if you
want it to. It's not just mediaplay that's special like that.