Sure, I could see a situation in which I fail to download something now and then it becomes no longer available on the iTunes Store at a later date. Then I'd be screwed. But that's a fringe event and not an insurmountable problem. Apple could send me email reminders 15 or 30 days after a purchase prodding me to download and back up locally lest tragedy strikes. Or Apple could add a checkbox to iTunes's preferences that says Never automatically download new purchases. (We'd probably have to agree to a disclaimer before turning that option on.)
This isn't the only iTunes-related problem that I think Apple needs to address. (Don't get me started on iTunes Match's track limit and all-or-nothing approach.) But it's a major headache for me--and judging by the replies and retweets I saw on Twitter, for others as well.
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