Clarification of my earlier statement (not that it should need any):
By putting them on trial and then convicting them of a "crime" that a lot of people don't consider a "crime" you make them into heroes, Rock Stars, lauded within the community that they represent. Once the conviction is then quashed at a later stage, they are not only seen as heroes, but as David's against the media "Goliath".
The victory of the prosecutors is pyrrhic at best. They've gained nothing but a short-lived victory, whilst at the same time giving file sharers worldwide exposure. They've further ostracised the very people who might be their customers now and in the future.
The example of Mick Jagger was apt in this situation for he was charged with an offense that his fans, and many others in society, thought was ludicrous. The victory of the prosecution in that case did nothing but gain The Rolling Stones more fans and popularise the idea of smoking pot. Make it "groovy" if you will