Your argument doesn't do your opinions much justice.
I agree with your assertion that some people freak out about mundane things (for various values of mundane) when they probably should not. I also think getting too overworked about these things is hilarious. However, may I ask, what is the harm in the small, vocal minority of people that do freak out about every-little-thing in doing so? Would it be more beneficial for society to not have these watchmen, or - in your opinion - loonies, voice their concerns? You do, after all, have the ability to ignore them like they have of you.
In all of the posts that I have read under this article, not one of them would I attribute to the crazy, tin-foil hat societal fringe you describe slashdot as being comprised of. This book may, or may not, happen to have been written by one of these excessively paranoid people you and I find funny, but many of the posts on slashdot about this category of Big Brother and descent-into-fascism are well-reasoned and well-grounded in the reoccurring nature of history. One of the reasons why so many slashdotters make posts about Big Brother is because the technology being used to monitor us falls under one of their areas of expertise. Another reason they may post is that they feel we, as a people, should learn from fiction and history so that we do not repeat our past mistakes - or make them in the first place.
Specifically, on the subject of traffic and transit cameras, we feel that having a multitude of cameras everywhere in society does not foster an atmosphere of privacy and assumed innocence. Maybe we are overreacting now - maybe the amount these cameras can help society far outweighs the damage the may cause. However, reset the scenario for the generation after this technology was introduced when the next big advancement in surveillance technology occurs - assuming it does, of course. Are the next generation's fears that this new surveillance technology may be overreaching unjustified too? In addition to the future, we must also think about past technological innovations. Were concerns at the time these technologies were being implemented justified? If these technologies were abused, in what way were they and how did we correct for these abuses? Were the corrections successful? Etc.
The furthest out on the fringe are definitely hilarious. The paranoid, loony people that think the CIA are personally out to get them because they know about the Illuminati vampire plot to use the resurrected corpse of FDR to take over the world are just too absurd not to find funny. But the people on slashdot, for the most part, are not these people. Do not paint them with such a wide brush because their fears, while sometimes overstated and dramatic, are nonetheless relevant and justified.