while you may not support the company and it's methods, the point they are trying to make is more honorable: making the dmca more complicated is pointless.
They're not against making it more complicated, they're for making it less complicated and desirable for them, unless I misread the post. They're for making it "less complicated" with the goal of it changing to covering what they do entirely so Universal etc. can't sue them any more.
"...respectfully submit this opinion in support of such adoption..." (from the letter they want users to send)
Your complaint against them, in your original post, is a legal one. They are advising that action be taken such that they are no longer in such a precarious legal position, which would seem to appease the complaint you made. Absent other reasons to support your position (a few of the many potential reasons: "Copyright is a moral right", "I support the status quo against all comers"), I'm not certain what your argument is.
Edit: To further sate my curiosity: you have repeatedly said that Grooveshark "abuse" the law, which strikes me as a strange choice of word. Do you mean "break"? Or do you mean "they don't break the law, but I believe that what they do should be illegal"? Or something else entirely?
by abuse I mean they take a piece of law (DMCA) and then manipulate it. I absolutely suck at explaining things, so forgive me if it makes no sense, but imagine your parents said to you when you're a child "You can't watch TV after 9PM on a school night" and then at 1am you watch TV and say "but mom, it's not a school night, it's the morning!".
The way Grooveshark do it is by having users upload music, if they wanted to be legitimate they could easily require anyone uploading music to call and verify their identity (how many record labels are there out there?) but instead they have users upload and that covers them under the DMCA, so they can then make money off those uploads and when they're notified it's there (which they of course know it is, that's their entire business!) they say "oh hey, so sorry! We thought it was you uploading, sneaky users eh! We'll delete it now for you" when if they had wanted to make sure the rights owner was uploading in the first place, they could have done.
I have a copy of Rihannas latest album here, if I wanted to upload it to Grooveshark right now for other users to listen to I could, they could prevent that if they wanted but they don't, they use the DMCA to build their business off those uploads.
I hope that explains it, if not I guess I'll just have to give up :( I guess a simple way of explaining it is that without the DMCA, grooveshark could not exist.
Edit: Actually I thought of a better way to explain it, one that I think matches the idea of a hacker more. They had a problem: they needed to stream music to users and cover costs without having the rights to stream that music, they realised to be able to they'd need money and they didn't have it. So they found a solution: DMCA, that would cover what they wanted to do as long as they responded to labels who didn't want their music and they had deniabilty when it came to how the copyrighted content ended up on their service: users uploading.
So they had a problem ("how to stream music that requires rights to stream without those rights") and they found a solution ("dmca") and used the requirements of the dmca ("users uploading and removing when requested") to shape their service. Does that explain it better?
"I guess a simple way of explaining it is that without the DMCA, grooveshark could not exist."
But it does exist.
I don't see the difference in saying "without law X grooveshark couldn't exist" and "without law Y the RIAA lawsuits wouldn't exist", where law Y is current copyright law.
The copyright laws are what they are; there's nothing magical or sacred about them, so I'm failing to see how adhering to the DMCA is somehow crafty or slick or manipulative. (At least not any more so than current application of copyright law.)
'So they had a problem ("how to stream music that requires rights to stream without those rights") and they found a solution ("dmca") and used the requirements of the dmca ("users uploading and removing when requested") to shape their service.'
That makes what they've done sound entirely reasonable. They had a problem; they came up with a clever solution to it. It didn't even involve large monetary donations to congressmen.
