No.
First of all...iTunes is Apple's "thing." Second, iTunes (referring to the app on the device that actually plays the media) is not anything special. It is fine and does the job but so did my Blackberry media player.
I don't have any idea why a non-Apple user would want to use iTunes (for PC anyway). It. is. awful. It is a resource hogging, slow moving, average media manager. My family uses iOS devices but if I could cut the ties with iTunes on PC I wouldn't waste a single second more with it.
Next, any music or video purchased and downloaded from Apple can be easily moved to and used on other devices. At least that was my experience when I had a Blackberry. I cannot address the poor folks who invested in iBooks. I have never purchased an iBook title because I did not want to be locked into an iDevice to read books.
Finally, I need to say this to avoid upsetting the hardcore fans... I love my iOS devices (even if iTunes uck-says) and would not trade them for either a BB or an Android at this point. They do everything else very well.