Another reason DRM is unacceptable.
An increase in the security of the companies you buy your media from means a decrease in your own security. When your computer is designed to treat you as an untrusted party, you are at serious risk: anyone who can put malicious software on your computer has only to take advantage of your computer’s intentional capacity to disguise its operation from you in order to make it much harder for you to know when and how you’ve been compromised.
If you infect your machine with DRM (yep, even including your smartphone or tablet), you no longer own it — someone else does. And they can in principle and in practice do anything they want to do to it — all without your knowledge or consent.
Why anyone would want that, I haven’t a clue.