I think there are two different phenomena going on here. First, you have anonymous jerks making stupid comments and threats all over the web. No surprise there; people are less thoughtful when they don't have to put their identity behind their words. The second phenomena is when someone tries to make a name for themselves by criticizing something or someone popular. Again, no surprise; it's been shown to be an effective way to get attention.

I don't really have a solution for either of these problems, but I think it's important to make the distinction between these two cases.