That is unfortunately not what really happens. In truth the political establishment has been moving steadily leftward for decades under the influence of the mass medias, and not just in this country but throughout the West. The only Republican President of the last 50 years who has been even vaguely conservative was Reagan, and even he didn't do squat domestically.
You make a very good point, which is that the media propaganda machine, in cahoots with liberal political elites, work very hard to move the public views leftward. When they think the public is ready, they launch a new policy. They break down American society in stages--tearing down religion and culture and marriage, etc. We need a counter-reaction to take society back to policies that are better for society, that make us more cohesive, healthier and freer.