DRM is supposed to prevent redistribution of copyrighted works. That's the unethical part. If the user is not redistributing copyrighted works, why should the law care about the preservation of DRM?
If I buy a locked safe at an auction and it contains a bunch of copyrighted paintings, nobody would get mad at me for breaking the lock so I could get to them. What else am I going to do? Hang the safe on my wall? The problem only arises if I start copying the paintings and distributing them.