The "arguing in favor of a bad law by saying they'll just look at your intent" thing is completely invalid for the DMCA because your intent is the thing they don't care about. That's why it's such an absurd law.

Suppose you commit unambiguous copyright infringement. Then they could already sue you regardless of whether there is any circumvention and anti-circumvention is completely redundant. It has no actual purpose that exceeds what you would get from presuming willful infringement if someone had to circumvent copy protection and then having different penalties for willful and unintentional infringement.

But now suppose you don't commit copyright infringement. You make a fair use copy of the work. Completely different intent. They don't care. It's crazy.

Where this gets really wild is the prohibition on circumvention tools.

Suppose the copyright expires on a work previously under copyright. Happens all the time. You now have a bunch of works with a "technological protection measure" preventing you from copying them, even though they're not copyrighted. Your intent is now to publish a tool to help everyone remove the DRM from those public domain works. But maybe the same DRM is also used on other works that are still under copyright -- and you may not even know that. So does your intent matter or not?

To clarify by intent I mean whether the intent was to circumvent or not wrt strength of technical DRM not whether the intent was to use it fairly or not; nothing to do with morals or ethics. I make no comment on whether it is right, just, or absurd.