I personally know a lot of people who do not find iTunes unpleasant. They use the 1% of the functionality necessary to get their tracks onto their device and that, as they say, is it. They do not know what mp3 actually is, or any other music format. For them Hi Fidelity is a book written by Nick Hornby and a pretty good movie, and is only peripherally related to music. These people my friends, are the vast unwashed masses, who do not sip lattes together sharing their hispster experiences and waxing inteligently on trends in fashion, these are the people who are ARE Apple's customers. In some circles, these people are called consumers.
Disclaimer: I personally think iTunes is an abomination, but I am in the software industry, so my opinion is only relevant in the sense that I evaluate it differently from consumers. If iTunes was perceived as badly by consumers as I (and everyone here I think), then I suspect that Apple would never have been as successful in the music delivery business.