The main cause of the restriction of personal rights in the modern era is compensation for technological advancement and avaliability of information, more specifically the increased potential influence of the individual. If you lived before telecommunications existed (and especially before the invention of the printing press and the post) you basically had no idea how to do anything (other than the obvious: sowing crops, tending to crops, harvesting crops, etc.) without acquiring an apprenticeship, assuming you weren't a part of the nobility or aristocracy. Information had a much higher price per unit, and because you're a un-specialized feudal serf, you could neither afford it nor care about it, and doubly so you probably wouldn't have the money or access to the proper resources to use it correctly. Cut to today, where you could conceivably design a bomb (thanks to the numerous references avaliable online or at your local library) build it (thanks to the now-relatively wide selections of substances offered by supermarkets and online websites) and mail it to someone discreetly. Let's take this a step further. If you had the money, and there were no laws prohibiting you, how hard would it be to build an atomic bomb in your own house by yourself? I don't think it would be naive to say that you could theoretically complete a design within a few days and have the proper materials within a few weeks. Now, imagine you had to do this a few centuries ago. No matter how much money or immunity you had, you would still have to INVENT the bomb yourself due to lack of information, and then SOURCE things yourself due to lack of suppliers. (who is selling 1.32 moles of isotope-z in 1642?) The minimum cost and effort required would far exceed what is required for an individual today.
For a more mild example, how easy would it be for a single individual to perpetuate "harmful" (society-destabling) information? With our global meme networks (social media) and knowledge of human psychology, a task like this would be considered trivial.
As technology, commerce, and technique grow more powerful, so does the individual - a kind of more lethargic, fatalistic Moore's law. One man can kill hundreds with a small portion of his salary and a squeeze of a trigger. The same man can kill millions with a few dozen salaries and the tap of a button. Imagine what the world will be like when we find the next hydrogen bomb - the next most powerful exothermic reaction. What will the world be like? Perhaps it's time to pay attention.