I think it would be cumbersome for anything except entire CDs.
I can't tell you how easy it is just to grab my Ipod touch, boom, Itunes store, ten seconds later I'm listening to the song I want to buy, then I have my password punched in, and, boom. My new song is downloading basically in the time it took me to write this.
Songbird+Amazon Store integration=Faster as iTunes store.
When I find the song I want I press a button and I have it. And if amazon suddenly changed their policy on music I can change in two seconds flat to the myriad of other music stores available. iTunes your hooked onto their music store, on songbird I can use any store I feel like, even browse the web and download any .mp3 that I find in two seconds, with one press of a button. In fact I'm on the song bird browser right now.
From what my one teacher discussed about iTunes, it wasn't Apple's choice to have the music restricted to only their players. If you look at everything else Apple does, they try to be more open source with what they make... besides the OS being usable on any store bought PC.
I tried to install some extra RAM for a friend once. After an hour of trying to figure out why the silly apple will not appect it (Everything looked good) we broke down and took it to the apple store to tell them something was horribly wrong. They told us we needed to buy special MAC RAM. (Only about 2x the price of normal RAM) I'm never, ever going to use apple products.