It's well known iTunes adds a lot of services and crap on your PC. As an avid gamer, I want as little as possible running in the background to help my games' performance. I dont want iTunes swamping up my PC.
Second, the notion of being able to add / access files from only one or a few PC's is idiotic. It's not going to stop piracy. Even with my no-name-brand mp3 player, I dont take it over to my friend's place and swap a bunch of mp3s. People are still going to download the music illegally and then just transfer to it their ipod via iTunes. Disallowing access to the ipod from any PC wont stop the problem in the least..it's just a huge inconvenience.
I'm at work right now and just downloaded a podcast that I'd really love to put on my ipod and listen to when i go for a walk at lunch time. But thats right... I cant because I have no way of getting it on my ipod while Im here at work. This was a shitty decision by Apple imo.