A digital watermark is automatically inserted customer information into a purchased product to restrict it's usage only to the buyer of that product. To me that's exactly like Digital Rights (Restrictions) Management. Calling something that contains digital watermarks DRM-free is deceptive to the customer. But long story short, if it contains watermarks I don't buy it.
The watermarks are discreet w/ no other information than your name. The PDFs require no passwords and can be loaded on up to 6 different devices. We have tried to come up with a solution that provides for the customer, but protects our authors' content as well. But certainly I can understand your point of view.
They don't protect anything. Probably 90% of your catalog is out there on the net and findable with a bit of googling. In the end it's just a bad business decision. You scare away potential customers and your stuff gets pirated anyway. You're degrading your own product and artificially creating a situation where the pirated product is actually a better one (one without a watermark) than the one you are legally selling. You've got to realize how insane that is.