Scott Granneman does a good job of showing how DRM is bad for all and sundry. It hurts the law abiding consumer, causes ongoing irritation with the vendor (key marketing tip: irritating your customers is not a good strategy) - and, ironically, by blocking otherwise legitimate usage, it forces people to break the law in order to get around restrictions. An example - after buying a DVD archive of the "New Yorker" magazine, Scott found out that he could barely use it:

No dice. The issues were available as DjVu files. No problem; there are DjVu readers for Linux, and it's an open format. Yet none of them worked. It turned out that The New Yorker added DRM to their DjVu files, turning an open format into a closed, proprietary, encrypted format, and forcing consumers to install the special viewer software included on the first DVD. Of course, that software only works on Windows or Mac OS X, so Linux users are out of luck (and no, it doesn't work under WINE ... believe me, I tried).

Read past that - he points out that it's not that hard to get around these issues, but - based on the DMCA - you are committing a felony when you try to do that. Another key marketing tip: Making your customers felons is not a winning strategy. Read the whole thing, as they say.