Perversely, I only use iTunes on my PC because of... my car. My car has great iPod integration, with a dock in the center console that allows me to plug an iPod in, and then have the metadata for songs show up on the dashboard. It also has controls on the dash that allow you to navigate the menus, including a knob you can turn as an analog to the iPod wheel.
Since listening to music in my car is a primary use case, I'm then forced to use iTunes to manage that iPod, which makes using some other software to also manage music seem redundant.
As far as I can tell from speaking with my iPhone-owning friends, the ability to easily sync their iTunes libraries to their phones is a major selling point. And we all know that the music sync/playing experience on Android isn't really comparable. So this move would make little sense if Apple believe that iTunes' exclusivity on the iPhone drives a lot of phone sales.
On the other hand, there are now a ton of Android-owning people who would probably buy a lot more iTunes music and movies if it were available seamlessly on their phones. Seen that way this move would make perfect sense.
I'm not sure I'm convinced of the latter. It's probable that a lot of Android owners already use iTunes for music and movies and just copy it to their phones manually.