They aren't suing their fanbase. They were suing people that stole or were contributing to the theft of their game. Those aren't fans.
I can tell you from experience that some of them are, so yes they are, at least in part, suing their fanbase. For example, a fan who can't wait until payday to play the game he's been dying to play is still a fan, albeit an impatient one. The two categories of pirates and fans are not mutually exclusive. I know this for a fact since I straddled both groups for years. A fan who downloads the game to see if it will run on their machine (there was no demo) then buys the game once he is sure it will work is still a fan.
Your anger is directed towards people who just take things they want for free without ever paying for them, and I share that anger to a point, but even some of these people can be nudged to become customers. Not all, maybe not many, but some. I've seen it happen. Given that CD Projekt is a small studio with relatively niche appeal (though that changes with each outstanding release), I doubt they want to drive away people through draconian litigious efforts who could otherwise be nudged to being customers, or worse, wrongfully accuse a paying customer and lose him or her altogether.
Even if their method of identifying pirates was 100% fool-proof, and they dropped action against people who could show that they purchased the game after downloading (which they were allegedly doing, though I haven't seen it confirmed), I would still be 100% opposed to this method of dealing with pirates. It simply does not work, and is proven to be counterproductive. The announcement that they were doing this floored me, and dented my respect for them, but true to the excellence of the studio, they have done the right thing in light of the concerns of their fans, and I'm back to a full-on CD Projekt love fest.
And if it makes you feel any better, I have bought 6 copies of the game in total (5 as gifts), so at least the negative effects of 5 pirates has been negated. This comment was edited on Jan 12, 2012, 19:24.
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- Mahatma Gandhi