Surely cost benefit analysis has been ignored.
F35 against an advanced foe could be a game changer. Risking the same platform against a Toyota pickup is a nonsense, but necessary if that is the only weapon in the armoury.
If you have lots of other toys then you have a choice.
I was employed on an operation where the bottom line was we were not to risk loss of even one aircraft. No such stipulation was laid down for the other aircraft.