From what I have gathered watching this program; when the F-22 purchases ended, additional mission and functional requirements were placed upon the 35. The pundits have noted that this in turn led to further increases in the overall cost of each 35 which of course lead to the inevitable increase in the cost of each 35 over each 22. Add in another part (reasoning) and I am paraphrasing; the 35 was supposed to leverage off of the supply chain management, technology development, and other “economies of scale” of the 22. This did not happen of course and the 35 program ended up bearing lot of the additional costs along with the typical (sing the chorus with me, you know the words) “Typical mismanagement common with large defense projects”.
Reducing the number of 35’s produced also inevitably increased the per plane costs due to the non-recurring engineering, manufacturing, and testing costs.
This all circles back to the original primary culprit that initiated this entire vicious doomed cycle: “concurrent design/build” philosophy.