As someone who pirates a lot of movies and TV, I think it's hard to justify based on ethical arguments against the industry. At a certain point, it feels like a wobbly justification to say we like using something but refuse to pay for it, and that's actually fighting the good fight. Personally, I don't like some of what these companies do, but I like other parts—like the movies and shows their dark malevolence provides me. I have to admit that the real reason I pirate is because it's more convenient and cheap.
I would naturally tend to agree with you, and when it comes to DRM-free things (like most music) I totally agree, but I genuinely think financially supporting companies using DRM is unethical. I used to buy (and still would buy) a ton of ebooks and a fair amount of movies/shows, but at this point I refuse to. The only exception is Audible. I still buy a ton of audiobooks from Audible (unless I can find them on Downpour or another DRM-free site) because I think they've gotten to a reasonably happy medium on the DRM. I would rather they drop the DRM, but it's at least not a giant pain in the ass to strip for people like me who really care about that.
I strongly want to pay people for good content, and I think they deserve to make some money for their work, but as soon as they slap DRM on it to limit my ability to back it up, consume it on whatever device I want, etc, the scales are tipped and I think piracy is actually more ethical than supporting such shit financially.
I'm not sure I see the ethics argument re: how the limitations affect your ability to back up / consume / multi-device. Those things might make it not worth your time and money, they might make it a bad deal, but it's not unethical to accept a bad deal.
For me, the ethical dimension comes from how the DRM will be abused. By paying somebody who develops DRM, you're complicit in building something that may later pivot from protecting content to silencing dissent or preventing local-manual override in a hazardous way, and that's unethical. Maybe it's not right up there with biological weapons, but it's still one of those things that we should not tolerate.
