The problem that we have with freedom of speech is that people take that to mean that they can say whatever they want without repercussion. They believe that they can defame people, lie about them, harass them, spread hate, threaten, and otherwise bully and because they are only words it's all covered and okay. No harm no foul.
Freedom of speech and expression is great when it works to our advantage (i.e. the Federalist Papers) and disastrous when it doesn't (e.g. Ryan Halligan, Megan Meier).
I believe that we should have the freedom to anonymously criticize our government and government officials. I think where that anonymity begins to become cloudy is when it moves from political commentary (blog post, letters, manifestos) and into conversation (comments, forums, chat).
Think about it like this... If I write a manifesto that says that all brown haired people came from the mud and are some lower life form separate from the rest of humanity. I write it, put it out on the internet and maybe someone reads it and maybe someone doesn't. Maybe it resonates with a couple of people and we get a little brown haired hate group going. However, if I go onto CNN and post in the comment section of another article and express my hate for brown haired people and my theories about their origin, then it is part of a conversation and has a much different audience. That audience may include people who are trolling, just for entertainment, and believe it's funny to back up other people's crazy claims. So now I've posted my comment and 5, 10, 20 people start saying "right on", even though the first 4 or 5 people were liars or just kidding, other people start seeing the support and start questioning if they should be in on it. The more people who post, the more it seems "right" to others and the more their small discomfort around brown haired people becomes justified. Soon the number of people who would argue that it's wrong are simply drown out by the number of people who are there trolling for fun and the number of people who are simply following the anonymous mob and reposting the same thing over and over again. Moderators have a hard time keeping up without looking like they are censoring legitimate comments and unmoderated areas explode with nastiness.
The problem areas are defamation, liable, and slander. These issues, which were relatively easy to control in the past, can explode overnight on the internet. What was, at one time, simple bullying in the halls of a school between a few students can be inflated to hundreds of attackers because of the effects of anonymity online.
What we need is a mechanism to ensure anonymity for the known good aspects (political speech, government criticism, whistle blowing) and curtail anonymity for areas where we know it's not really useful or good. That's a tall order from a technological perspective, there's no easy solution. However, that doesn't mean that we should stop trying to think of ways to make things better (not necessarily legislating, but innovating). If we can't eliminate anonymity under certain circumstances perhaps we can find other solutions that curtail the destructive power of online defamation, liable, and slander, especially for those who don't have the resources to engage in lengthy court battles for reparation.