I agree, because DRM has potential to outlive copyright law. Sure, many DRMs are broken, but there are many that are not. As the arms race escalates, DRM will become harder and harder to crack (I can think of a few offhand that AFAIK have never been cracked publicly, like the encryption used on cable systems in the US). The people in control of the various DRM systems are not even thinking about future noninfringing use, because they're not even thinking about current fair use in developing these systems. These are largely people who do not think copyright should expire that are driving these anti-public efforts.
Also, think about what a waste of talented peoples' time this represents. Probably many person-hours are spent implementing these increasingly sophisticated DRM systems, and then many more trying to crack them, rendering all of it completely pointless.
You’re right, I never thought about the long term effects of DRM. But we’re really just talking about its effects on our grand children. To be fair we’ll all be dead by the time works made today will go into the public domain.