First: Copy protection does not work; it only punishes legitimate users.
First, part two: it punishes legitimate users because there will be false positives. At some point, someone, somewhere will get locked out of a copy of Spore or Mass Effect that he has legitimately purchased, because SecuROM will make a mistake. Meanwhile, no pirate anywhere, ever will have any trouble getting them to run. Which club do you think I'd rather belong to?
Second: security. It prevents me from deleting 16-bit binaries from my computer. Oh, hello Mr. Gaping Security Hole.
Second, part two: Sony does not have a fucking stellar record when it comes to DRM and security flaws.
Second, part three: by its very nature, any software that is designed to hide from a user who installs it and which is not easy to remove introduces a vulnernability in the system. Especially if it, oh, say, cripples your antivirus software in the process.
Which brings me to third: it's been known to damage the functionality of people's systems. Development software, CD burners, and antivirus have all been affected, plus it deliberately blacklists software for mounting disc images, something that Mac and Linux users tend to take for granted as a basic part of their OS. And that's just the stuff we know about -- who knows what other unintended (or even intended) consequences the software could have?
First, part three, and in summation: I do not appreciate being treated like a criminal.