That's pretty much exactly what piracy paranoia always does: screw over the folks who play by the rules, without hurting the pirates at all.
I can't call it a simple case of that, for the following reasons.
First of all, did any of the honest people do anything to stop piracy? Did you report any torrents to WoTC? Did you try to encourage people not to do it. Did you explain to your friends about this? I'm sure some did, but I'm sure others didn't and even encouraged piracy, while others turned a blind eye. And those that will now "turn to piracy" to spite WoTC don't really have, IMO, a very good grip on ethics or morality.
Secondly, this does deter pirates somewhat. The WoTC benefit from printer proofs and Acrobat features. Somebody would have to scan the physical book and it's likely to be an inferior copy.
And thirdly--I fully suspect ISPs and other will start being able to detect piracy. Let's see where we are 10 years from now.
As annoying and disappointing this is, I have a feeling that you'll be seeing more of this occuring. Today, the AP announced they are taking steps to prevent their stories from being used without compensation--in part to protect their newspaper subscribers.
The two biggest problems with the Internet revolution were the following: companies focused more on market share rather than how they got paid, which gave an expectation, and people like Stallman, Lessig, etc., started a memeplex that made people think that created content was worthless and should be gratis for people to use. This has created a sort of entitlement culture in the world, as well as enforcing a somewhat naive belief that people should create "just for the art", and that any big corporation that produces content is evil, IP laws are "stupid", etc.
I suspect the economic downturn is going to cause some harsh realities, and you can expect more companies making these unpopular decisions.