I think that America faced a variety of problems contributing to what Carter has been mistaken as terming a "malaise" in America. The exuberance and optimism that was present in the 1950s and the intense clamor for social change that was an animating force in the 1960s seemed to both dissipate into a sense of the unknown and uncertain in the 1970s. The Vietnam War's escalation and interminable condition dominated the opening of the decade. At the same time, there was a genuine feeling that the Russians had it "figured out" in terms of the Cold War, as America struggled with the shadow of Vietnam and the spilling over of conflict into the other nations of the region. To a large extent, Vietnam and everything that emerged out of it helped to bring to light how America could not really stand as the representation of purity in advancing democratic sensibilities. The use of covert operations, "black ops," and "military advisers" and "puppet governments" all helped to reduce America's leverage from an international point of view. At the same time, the Watergate Crisis impacted Richard Nixon's ability to conduct any semblance of foreign and domestic policy, feeding again the issue that the Russians had it "figured out" over the Americans. Brezhnev never had to deal with bugging devices in the Kremlin. If he did, two reporters named Woodward and Bernstein never dogged him or members of the Politburo about their functions.
At the same time, economic concerns impacted America in the 1970s. The concept of inflation, long gas lines, and intensely struggling to find a sense of identity was something that presented itself in all forms to all Americans. One of the consequences of the massive social movements in race, class, and gender from the 1960s into the 1970s was the inevitable question of what one actually does with freedom. The concept of struggling to gain independence and the reality of achieving it leaves a sort of gap of wonderment where a sense of questioning presents itself. This is certainly where America was at the time of the 1970s, where self examination and self doubt translated into a sense of wondering about one's place in both domestic and international sense of the world view. The fact that Archie Bunker from "All in the Family" was a popular figure helped to tap into this idea that the "whole world" was "off its rocker" and so little seemed to make sense. In trying to contrast itself with the zeal and optimism of previous decades, this fed into the domestic image of self. It made sense that someone like Charles Manson's trial would take place in the 1970s, when "Helter Skelter" was a description of how people viewed themselves and their world.
The Presidents after Nixon did not do much to help America's self image. It seemed that Ford and Carter operated as mirrors of American insecurity and doubt. Each time Ford fell on stage or tripped up stairs, it served to enhance America's own sense of clumsiness and awkwardness. When Carter claimed of being unfaithful in his heart or when he collapsed into the arms of security guards after a jog or when he sought advice from his daughter, Amy, on the nuclear crisis, it seemed to enhance the nagging fear in Americans that both they and their leaders had no idea what to do or where to go or how to function.
In the end, these were the realities that dominate the 1970s, a time period where a charismatic bad actor from Hollywood was considering his greatest "acting" job yet.