Lonewolf and others,
I've posted this before, but it might help to repeat it.
The JSF/F-35 programme was a US Department of Defense (DoD) response to a series of failed tactical aircraft programmes in the 1970s and 80s. (NATF, AX, A-12, etc.) The military (and their DoD technical advisors) came to the conclusion that as long as the USAF and USN were trying to buy large twin engined aircraft, the risks of weight growth, and associated cost growth, were just too great. The F-22 programme just served to underline the fact that even the USA could not afford to build large aircraft of this type.
The solution developed (within the DoD's OSD) was to force the next generation tactical aircraft to a single engined single seat configuration to constrain weight and therefore cost.
This policy was implemented via a series of steps which included the STOVL Strike Fighter (SSF) project for the USMC, CALF, JAST and on to JSF. The main technology enablers included a next generation engine (lighter and more fuel efficient) and fully networked mission systems with ab highly advanced sensor suite.
You can disagree with their reasoning, and point out where you might think they've gone wrong, but that's basically what happened. In this case, I don't think you can pin the blame on the politicians.
The USN, by the way, have consistently (since around 1997) declared their policy of buying Super Hornets until the F-35C comes along, and then operating a mixed force. And they've always said they'll flex numbers to fit the F-35C programme. In retrospect, they have done a good job a managing their tactical aircraft fleet (Incidentally, don't forget how many times the Super Hornet came under the spotlight with flight test issues)
The USMC will manage their AV-8B fleet as best they can (buying up the UK fleet helped them a lot) until F-35B comes along. It's later than they wanted, but they'll suck it up.
In my view, the USAF are in a bad corner as their F-15 and F-16 fleets are ageing fast and aren't going to last much longer. This doesn't get much reporting, but they've spent billions on two attempts to extend F-16 fatigue life with not much to show for it. They have already lost early F-15s to fatigue failures. Doesn't necessarily make them bad aircraft (I think they're great aircraft) but they are not getting any younger.
Hope this helps
Engines