I could understand it if they used Gnome2 as the foundation, and added to it, but they didn't.
That makes so little sense I can hardly believe you actually wrote that. Basically, the major (visual) change between Gnome 2.32 and Gnome 3.0 is that Metacity and gnome-panel have been replaced by Gnome Shell, in the default configuration that is. Did you really think that the Gnome developers put thousands of man-hours of development effort in the trash and started over from scratch?!
I open a Konqueror window w/ the folder that has those music files - be they mp3, wma, m4a or whatever, and I just put my cursor on the file - don't even open it. As long as my cursor is on top of it, the song in question plays. If I move my cursor away from that file, it instantly stops. If I wanted the playing to be uninterrupted, I'd go ahead and open the file in question w/ the music player of my choice - and under KDE, there are some 6 or more of them, not counting the video players. It's not doable under Gnome 2
Funny that you should give that as an example. Nautilus has been doing the same thing since at least 2004, probably earlier.
"God is a comedian playing to an audience too afraid to laugh." - Voltaire