Sure, they don't force you to buy music from iTunes, sure, but they do control the way the user generally uses it. iPods appeal the most to the non-technical crowd, who probably don't know, for example, that the Amazon mp3 store exists. iTunes is much more a store than a music player. I'm not saying its unfair, but its not like its the most open system either. It's like MS doesn't force you to use WMP or IE, its just what's most likely going to happen for the average user.
Also, if Apple REALLY wanted a DRM free store, then it would be. Amazon REALLY wanted it, and they have it, and Apple has far more pull in the digital music front than Amazon does.
By the way, neither mp3 or aac formats are open. Both require a patent license for manufacturers and developers. ogg is open, and Apple does not support it at all as far as I know (it was definitely incompatible with iTunes in the recent past).
Finally, Apple's philosophy is to make money. That is the be all and end all for companies. NEVER romanticize this. I will give Apple that they have a great skill at image control, but they are just as ruthless as Microsoft when it comes to making money, MS just got the upper hand first so Apple can play the less evil underdog.
My bias: I use Linux (usually Ubuntu) for leisure/small tasks, XP and Vista 64bit for gaming/study/real work, and OSX at my part time job as a creative person, and honestly, I like OSX the least by far. I also disapprove of the abuse of the word irony.