No one ever said it was (an air superiority fighter)
Not in so many words, but you folks are certainly demanding it have the maneuverability of an air superiority fighter. It doesn't because it isn't.
I'm aware of what the A-7 is, thanks, but I'm just guessing that most of the countries signing up for the F-35 are not looking for a 21st century A-7.
Well then, I'm guessing the you're guessing wrong. Do you really think the Royal Navy (and the other F-35 buyers) think they're buying F-22 dog fight performance? REALLY?!!
The problem for most Western nations though (and the US to a certain extent) is that in the coming decades it will become the sole or predominant platform in their inventories.
Yeah, that is a problem. But not one caused by any F-35 design fault. The airplane is (mostly) meeting all its performance requirements. If a "Western nation" has put all its eggs in the F-35 basket and finds that it comes short on capability, that is a political problem, not a technical one.
And about the US fighter inventory, the F-35 will NEVER be the sole or even "predominant" platform in the USN inventory. The USN will always (well, until they are retired) have far more Super Hornets than F-35s. And USAF is planning on keeping their F-15s flying till well into the mid-century when the next air superiority fighter should become available. And USAF will be flying the F-22 till later than that. So there are at least two Western air arms that fully understand what the F-35 is and what it is not and have planned their inventories accordingly. If other air arms don't understand that (as you allege, but which I rather doubt) then their leaders need to be sacked. Perhaps shot.
Unfortunately for the F-35, as the old adage goes; 'You can make a bomber out of a fighter, but you can't make a fighter out of a bomber'.
You're still missing it aren't you? F-35 is predominantly a tactical bomber. But one that can escort itself to defend itself against fighters. It is not nor was it ever meant to be an air superiority fighter.
The F-15E is not an air superiority fighter.
I my goodness!!! The F-15A thru D are air superiority fighters. The F-15E retains essentially ALL the A thru D air to air performance while adding significant air to ground performance the A thru D lack.