Back when I was a big VX onlooker a couple years ago, I noticed something pretty quickly: most of the people who write those viruses don't do it for malicious purposes. If you look at some famed works by ones such as Z0MBiE, GriYo and the like (google it,) you'll notice a lot of their works are simply proof-of-concepts.
They're generally made to prove a point rather than screw you over, which is why many viruses distributed amongst the VX scenes these days also have source code many times, and in many cases cases, people write papers over their viruses (google "vx 29a".) The authors generally attach non-liability clauses to their released code (naturally,) and I can bet you in just about every case, the authors aren't the ones who release the virus anyway.
In plenty of cases, the people who write viruses and the like *aren't* the ones who distribute them. I'm not saying there aren't people who don't do this, but it's kind of a PITA for those who write and distribute such work (for generally nothing other than the spread of knowledge, think open-source) to be hit with such infamous blame.