Yea... It's an issue. You won't be able to put music on an iPod via WMP, without some plugin or rooting the player and putting a different firmware on.
I hated my iPod just because of this issue. I caved in and installed iTunes, which then ran into issues of those pieces of software fighting with updating the ID3 tags of my music. Had to dig through the settings on each to turn off auto update the ID3 info.
The happiest day of my life was when the iPod died, then shortly after my iPhone died. Which forced me to look elsewhere for new devices.
I had been avoiding the iPod / iTunes thing for years when I first saw my friend taking his music, burning it onto a CD and then re-ripping it back into iTunes and I said, "What the hell are you doing?" He explained that that was the only way to remove all the restrictive bull**** that Apple imposed on his music files. What a waste of time.
And now here I am 7 years later and I encountered my first iPod (I married into it), which unfortunately is seemingly the only device that my car recognizes, so I thought I would give it a shot and try to put my music on it to play in the car. Wow, all my fears were confirmed. There is no way outside of iTunes to do any file management or use another music manager. Plugins won't recognize the device either. So I downloaded iTunes and I've got to say, WTF? What a terribly designed user interface. It is a huge chore to do anything like simple file management. I complained to my wife and she said, "No, it's easy, you just plug it in and it syncs everything automatically!". And, alas, I understood why iPods got popular: 90% of users out there no nothing about how to use computers and they really liked the simplicity of the plug-and-auto-sync (which other devices can do too, by the way) feature. I think I'm just give up.