As a Lt Col (pilot) in the US Air Force, I can tell you that the F-22 is a wholly irrelevant and wasteful expense for the wars that we are fighting today.
Just as a fire truck is wholly irrelevant and wasteful expense, when there are no houses burning down. Think about it--that fire truck is damn expensive, plus you need to have some place to put it, and you need to spend more money paying people to know how to operate it--and for what? If there aren't any houses burning, what a bloody waste!
Ah, but what happens when somebody leaves a pot unattended on the stove and the food catches fire and lights the curtains on fire, which soon gets the walls and ceiling going and then the whole building faces the potential of being engulfed in flame? Suddenly that extravagant fire truck starts looking awfully necessary--particularly if it's your house!!!
Yes, the guy with the explosives in his underwear isn't affected by the F22 one bit--any more than he's bothered by our nuclear submarines, etc. But as certain powers shrink from their onetime standing the world, other powers are ascendant, and not all of them are benign. Picture a future scenario where North Korea, staggering under years of starvation and isolation, believes it is facing extinction, and comes to believe that its only recourse is to invade and capture a greatly weakened South Korea. The south has far more natural resources, and the terrain in the south is far more conducive for agriculture, plus there is a cultural tie there as well.
So, one of the world's largest armies sweeps across the border, overwhelming the opposition, which has been gutted and drastically weakened by many years of military cutbacks, political compromises, and the distraction of wars elsewhere in the world.
As the northern forces push southward, the US (perhaps backed by some UN allies) determines to halt the advance, reinforcements arrive, and eventually succeeds in pushing them back. At some point, China becomes threatened, and rolls into the conflict, ostensibly to protect its own interests and ensure a viable communist buffer state on its southern border.
That is almost exactly what happened during the Korean war in the 1950s, and it could easily happen again. Should we find ourselves fighting on the Korean peninsula, we will likely be outmanned on the order of 100-1, and the Chinese would bring a fair degree of sophistication to the aerial battlespace. Under those circumstances, it is the F22 fire truck that would be the only thing preventing a complete rout. As long as aerial superiority can be maintained, then our forces on the ground would have a huge advantage in terms of combat air support, aerial logistics supply etc. which would hopefully more than offset their huge disadvantage in pure numbers.
And that is why the F22 exists. Do we need to buy hundreds more of them? No, arguably, a smaller-than-optimal number is the most reasonable course of action. After all, you don't need a fire truck parked on every block in the city.
The military has an awfully difficult challenge before it right now. While we still need to be trained and equipped to handle the big threat (conventional war with a near-peer power), we also have to contend with the asymmetric warfare that we're embroiled in now--arguably a much more difficult task, and one that historically we haven't succeeded in (witness the ultimate success of the illiterate peasant Viet Cong).
It's fascinating to me to see how we are leveraging our strengths technologically (with armed Predator drones etc.) in an attempt to offset our huge disadvantages, i.e a profound lack of understanding of the local culture, language, etc. While doing so has enabled us to emerge victorious from virtually ever tactical encounter, strategically we still have a very long way to go, and ultimately it will be the responsibility of our almost completely hollowed-out state department and intelligence agencies to secure anything resembling a victory. Whether that will occur anytime before my retirement in 2018, is anybody's guess....