It's generally misleading to think about things as they are at a single point in time. The defining characteristic of our universe is change. From the laws of physics through the history of man, from cake batter in the oven to religion is there anything that doesn't change?
I think this idea can be particularly important in dealing with people, especially at the level of societies. Anti-racketeering laws intended originally to give the feds a legal weapon against the mafia have since been used to fight illegal immigration. The Expos even tried to use racketeering laws against Major League Baseball. The zeitgeist of a society is important for the people living in it at that moment, but the repercussions can echo deep into the future. The excesses of consumption in the last few generations may become a folk story used to teach children centuries hence.
Thus its important to understand how a society can change. In America, we have well defined rules built into our government for enacting change. Those tools are only available, however, to our legislatures and governors. Society as a whole has blunter tools to enact change in the government, election mostly, but has a great deal of freedom in defining civil society in an ad-hoc and emergent fashion.
Thus each individual has a set of options available to them to enact change, and differing motivations to do so. At one extreme, armed overthrow of the government has always been available as an option, should it grow dangerously oppressive. But such an action would require an extremely motivated core, a generally sympathetic populace, a popular opinion that does not condemn such actions. History has shown a preference for subtler evolution, but not universally.
Which all leads to my main point: changes at one point in time alter the possible changes at a future point in time. Consider Britain, with its increasing levels of surveillance. Detailed understanding of the actions of each individual in a nation can be used to stifle the emergence of dissent. Individuals really only influence the world by influencing enough other people. If a government could identify those seeking to change it, whether by legal or extralegal methods, they could imprison or otherwise isolate those individuals. Change is still universal, and spontaneous uprising is possible, but the growth of government often either directly or as a side effect limits individuals ability to influence the world. If the government at that time is a positive force, and the limitations on influence are presented as limitations on villain's ability to destroy, people can be willing to accept the restrictions.
Change is like a rug that doesn't fit in its room, though. You can push down the power to change the world in one place, and it grows elsewhere. By restricting the ability of the general population to change society, the resistance to changes enacted by the unrestricted party is reduced. And even if the people with all the power are good now, remember the universality of change. Thus, sooner or later, we can expect those with power to use it for their own ends. The less power society has been left with to resist, the more those in power can exploit.