I think you're allowed to make your own reasons up :) The man behind it is Bill Drummond, and his reason is that it's a day in which to consider what you want from music. This is pretty much my reason, as expanded upon last year (http://venta.livejournal.com/212520.html#cutid1).
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Date: 2007-11-21 11:14 am (UTC)(I've been observing it too, but only coincidentally thus far.)
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Date: 2007-11-21 11:20 am (UTC)