Because the mainstream media told us to!
To me, it's not an issue - as others have said, laws are in place to work against out-of-control behavior, whether it's offline or online.
Trying to make something that's already illegal, even more illegal, does not work.
What needs to happen is that people need to stop reading the useless blogs. There are way too many blogs out there that write and engage in "extreme" behavior simply for the traffic. People go and read them so that they can tell their friends "OH MY GOSH, DID YOU SEE WHAT THIS PERSON WROTE?".
In other words, the trolls are being fed and they feel they have a little power, and they decide to exercise it against the lady in the article. Yes, there could be one or two or three that are dangerous, but then again, many people on the internet are only talk and just that - I've seen people act like 6-foot-6 320 ex-football players online, only to find out they are 5-foot-5 140 pound scrawny types.
One thing I think some should think about it, and we've talked about this in other threads, is that many of us do use the privacy features when registered our domains, and we generally tend to keep personal information off of our blog. One could have a "personality" on their blog, without telling the world where they live, if they have kids, what they drive, etc.
Because we can reach many countries in the world, outside of the Chinas and North Koreas and parts of the Middle East (depending on our blogs), we also have a little bit more insulation. Even if we reveal our names and location. Somebody who gets angry half way around the world has little chance to do anything.
Now if you are blogging locally, or you make yourself a lightning rod, and you travel around to various events, it can get dicey if you are giving out your personal information.
It's a complex issue, but more regulation is not the solution. Common sense is.