More and more personal, private information is being used and stored online than ever before, and at the same time, attacks on that information are increasing in frequency and sophistication. Phishing is a growth industry—it's very profitable to trick people into handing over names, passwords, credit card numbers, and so on, so that their finances can be pillaged. Important activities like banking and filing tax returns are being performed, and these need strong proof of identity. On the other hand, there's no reason why a storefront like, say, iTunes, needs to know your identity; it only needs to know that the money being handed over is yours to hand over.
