Ray Beckerman has posted the most definitive guide to the RIAA's practice of scaring the wits out of consumers with copyright infringement lawsuits. At the crux of the strategy is the realization that many of the "John Does" in each suit may not have ever downloaded a single song -- illegal or legal -- from the web.
Because your average small town lawyer or "pre-paid legal" attorney has no idea what to make of these odd notices and subpoenas, even the defendants that seek legal help often end up "in default," and subjected to settlement demands of thousands of dollars. Defendants that get some informed help find their cases get mysteriously dismissed -- precisely so no case law will ever set precedent that strikes down these practices.
What all of this does is reinforce the idea in listeners' minds that musicians don't need any more money and don't deserve support. In the mind of the average music listener, there's no distinction between these large labels and your average indie singer-songwriter.
So, whenever an "RIAA sues another grandma" story shows up in your local newspaper, that story takes a ding out of musicians' revenue. All for the sake of the belief that music purchasing is a zero sum game.
Educate your fans on what you get when they support you, and how their financial support (by purchasing CDs, tickets, and merchandise) directly contributes to making more music and not subsidizing silly legal maneuvers.