Yeah, Simmons is understandably angry about people pirating music. It's his music after all, he made it, and he would like to get paid for it.
But it's a stupid move to threaten anonymous. Yes, they'll more than likely get some of the hackers, but there's no way they can get anywhere close to most of them, because it would be too difficult and too expensive to track down each and every single pirate, hacker or anonymous member.
But also, it's silly for anonymous to get so angry over a speech Simmons made. Lots of artists and lobbyists have made similar speeches, and threatening to "take down a website" isn't going to make the suits go away any time soon.
Both sides are over-reacting and making silly threats at each other. Some people, however, might have their lives ruined by this stupid argument, or at least they might lose a whole chunk of money.
It would be nice to live in a world without pirates. But until someone can perfect a form of quantum cryptography (which isn't as far off as you might think), pirates and hackers will ALWAYS exist. Rather than try to imprison all of them (and they will never be able to do that) or try to crush them out of existence, the industry must evolve with technology. It's not as if pirates are such a threat that they aren't making money any more - the record industry still does make money. They can afford to try to work around the problem, instead of relentless attacking it, which won't get them anywhere.
I am quite technically apt. I could pirate a lot of things. For example, Fallout New Vegas - I could pirate that fairly easily. But I'm not going to. You know why? I like Fallout, and I like Obsidian. I could have pirated the Orange Box or Portal. I didn't, because I like Valve. I could have pirated Mass Effect 2 - I didn't, because I genuinely want to support BioWare.
Musicians could easily beat the pirates by giving people a reason to buy the physical disk. Like, new artwork, free concert tickets with a purchase, or some sort of nick-nack. True fans of the musician would buy these things. The Film industry could combat piracy by making the cinema experience better (No, not 3-D however, that's bad) and giving people a reason to want to go to the cinema. I go to the cinema sometimes because seeing it on the bigscreen with friends makes all the difference sometimes.
I don't like pirates as much as the next reasonable guy. But I recognize that they're not going to go away any time soon. I think studios and the record and the games industry should try to take down the providers of illegal content or the managers of sites that provide illegal content - that at least has some merit. But in trying to take down anyone who downloads, they have set themselves up a fruitless, hard task that will not stop the problem, and will damage their image, which is often the most important thing a studio/musician/actor has.