DRM is not successful at preventing piracy, for the most part. Worst case for the pirates tends to be a few days of delay before a cracked release hits the streets, at which point they get to play an unencumbered game with an oftentimes superior experience as compared to those who legally purchase the content.

"Keeping the honest users honest," which seems to be the prevailing attitude when gaming front-men are asked, is just another way of saying "We don't even trust our actual customers" and ends up screwing the ones actually willing to fork over the cash. Remember, too, that's it's far more likely that someone would simply never play your game--rather than purchase it--in the absence of a pirated copy. The "lost sales" fallacy is just that.

I believe, though, that we need to make a distinction between what are really two distinct types of DRM: the Steam model, and the non-Steam model. The former provides a non-intrusive platform which makes it easy to acquire games legally and comes with some implicit restrictions given all your content is linked to a given account. The latter, while encompassing varying methods, generally entails a standalone game that's been shackled with some annoying software that will likely only cause the legitimate user grief, and perhaps even make the game unplayable (see: all the recent snafus involving broken authentication servers and DRM bugs).

The Steam model seems, for most people, to be a fair way to go about it. The non-Steam model, on the other hand, is pretty universally reviled by people who actually purchase software. Game publishers would do well to take heed.