"If an individual wanted to take action, in a way, it's even more difficult, he said. Individuals "can only claim compensation for damage that has been caused, and it's difficult to show what the damage would be from an individual spammer--you might be able to show you had to buy a spam filter, but you can't show it's because of that one spammer."
Microsoft had a definite advantage here, not only due to its financial backing but because the spammer was utilizing Hotmail, a service owned by Microsoft. Perhaps one day spam will light someone's house on fire and then they'll have more basis for a lawsuit. Either that, or laws will have to change.