You are forgetting the most important part here: memory! Since you are getting pleasure from those songs, it is only fair to make it impossible for you to just

You are forgetting the most important part here: memory! Since you are getting pleasure from those songs, it is only fair to make it impossible for you to just remember a song and hear it in your head over and over again without actually paying for it!! And it can all be wrapped into a neat package where you can license music and you can listen to it and then when you don't want it anymore, it can be burned out of your memory so you cannot mis-use your memory of it!