Why I paid £0.00 for Radiohead's In Rainbows

• Because I could. It's not often you get a *legal* free lunch. Besides, the download 'n' donate model is basically a marketing tool for the upcoming pay-for physical product. So in this context a free 'try before you buy' download is very much in the spirit of the objectives of the promotion.
• To send a message to the majors. Apart from a marketing stunt, this was an exercise in economics - to see what happens when you allow the market to set the price point (in this case ~£4.) Driving down the average price lets the majors know that their current wholesale pricing models are ridiculously over-inflated, and largely responsible for piratical can of worms they've been trying to litigate against over the last seven years or so.
• Music is moving towards becoming free and fungible, so why resist the inevitable?
• Radiohead don't need the money. They're millionaires many times over, so why swell their coffers even further? If they don't need the cash, why not simply give the album away for free? I'd rather support smaller up-and-coming acts with my hard-earned-groats (which I regularly do).
• Radiohead are more evil than you think. Their manager Bryce Edge went on the record in a Music Week article claiming that the download 'n' donate model was a mechanism to drive CD sales, and implied that the audio files were encoded at a low rate to ensure that punters would not receive the full listening experience. He even went so far as to claim that CDs were underpriced and should retail at a premium price point.
• I'm not a big enough Radiohead fan to pay for the album as a CD purchase (though I might rip it from a mate), so why pay anything for it now? That's double standards, surely...