Those are fair points. I think you're saying that my central thesis is that the American people were ready for a change by 1960. Upon reflection, I do think that's overstating it a bit. However, I think you're overstating Dwight Eisenhower's personal popular with the American people in contrast with their satisfaction of the state of the country. You'll note that I did say later on in the post that I did think Dwight Eisenhower could win.I find your central thesis doubtful. Polls showed both candidates in a dead heat throughout the race. Moreover, Kennedy won so narrowly that any number of factors would have swung the election to Nixon: if Nixon had decided not to campaign in all 50 states, if Nixon had not debated JFK, if Nixon had picked a better running mate than Lodge (who was gaffe-prone and did nothing to help Nixon win Massachusetts, where Kennedy had beaten Lodge for the Senate in '52), if Kennedy had picked any running mate other than LBJ (who was most likely the one reason Kennedy carried Texas), if Ike had not been so tepid in his support for Nixon, etc.
In spite of the recession, many Americans were still satisfied with where the country was going under Eisenhower and Nixon could very much have won had he made different decisions during the campaign.
I cite Allan Lichtman's Thirteen Keys to the White House theory a lot but these were the circumstances going into 1960 for the Republicans:
* Poor House midterm showing in contrast to the previous midterm. Democrats gained almost fifty seats.
* No incumbent President running (whatever).
* Real-per-capital does not equal or exceed previous two administrations.
* No major policy change. Nor in the previous term.
* Foreign / Military Failure. The public failure of the U-2 plane going down.
* No Foreign / Military Success to contrast.
* Richard Nixon does not have the charisma of President Eisenhower.
I'll leave off John F. Kennedy's personal charisma because I think that's a double-edged sword. His Catholicism worked against him but it should be stated that Kennedy essentially ran to Eisenhower and Nixon's right by charging them as being soft on Communism.
But really, think about this: a poor House showing, poor short-term economy, poor long-term economy, no major policy initiatives, a public failure on the world stage, no major successes on the world stage, and an uninspiring candidate. That's not fertile ground for an incumbent party to keep powers. These are the factors that matter more than day-to-day polling.