3. The burning need:  time marches on.

Metal fatigue will make our current aircraft completely incapable in another ten years.  Most would still be capable of flying, but not under combat loads.  Remember, longirons are failing, and old all-metal planes are already breaking up in mid-air.  Those that aren't breaking up are still requiring ever more hours in detailed maintenance and upgrade facilities -- reducing availability across the board.  Worse, retrofits only postpone the inevitable ...

Procurement Lags:

As to new aircraft:  remember we need time to get procured equipment fielded, into battle plans, and into exercises so we really know how to use them – not just theoretically (or even in computer simulations of theory). 

In a decade, could we win with current aircraft supplemented by F-22s?  I doubt it.  But I pose that the cost would be horrendous if we did win.  China in a decade will not be a pretty adversary.  Our current fighters will strain mightily by then;  'in a decade' is when China, Russia, and Islam all pose foreseeable threats far greater than today’s world poses:

 - China WILL seriously threaten our interests in Taiwan, not to mention Korea, Japan, Philippines, Singapore, et al.  China will threaten with quantity of modern aircraft and (more ominously) relatively inexpensive high-tech air defenses that will seriously hurt us.  Already, China possesses anti-carrier weapons that will keep our aircraft carriers at arm’s length.  With 1970s-era airplanes, plus a handful of stealth at far-away Guam, Air Force would have nothing to offer, to replace ‘persistent’ air presence China is increasingly forcing the navy to position ever more distant (in event of war).   

 - Russia’s re-emergence will have re-armed that country, which may not be all that friendly.  Worst case:  xenophobic ultra-nationalists (a Russian historical tendency), whether with a resurgence of 1900s atheistic communism or not.  Best case:  western-friendly leader like Gorbachev or Catherine the Great, who would actually trust and welcome a western alliance --- an alliance that maybe we could make actually useful to Russia and it’s long vulnerable southern borders.  As if Russia's gradual transition from President to Dictator isn't worrisome all on its own, recent international events in Iran, Venezuela, Cuba, Georgia, and Ukraine (among others) indicate Russia's western-friendly leaders are about as scarce as USA's conservatives have been in the last several years.

 - Islamic countries’ oil income could indeed well-fund militant Islamic resurgence like we’ve not seen in 600 years.  I propose this is an Islamic funding decision made more likely if we slide along with old all-metal fighters that they can counter with metal-seeking and heat-seeking hand-held SAMs.  That oil is also a potentially lethal chokehold on Japan, and would severely hinder us (the USA) and our European allies.  We have the ability to drill and solve that problem, except for environmentalists --- but that’s another dissertation.  We also have the spacefaring technical ability to dramatically reduce oil needs in non-vehicular uses, which would entirely remove the petroleum stranglehold by reducing the petroleum quantity needs mostly just to vehicles --- but this too is another dissertation.

c.  Why now??

Some say our current fighter aircraft fleet can serve us well for another decade.  Good!!

We will need that hypothetical decade, to acquire stealth aircraft in sufficient quantity for any big fight we hope to fight from navy carriers as well as from allies’ land bases.  A decade from now is when the current monopolar world doubtless will have changed again…

Again, most F-22 presentations concentrate on high-end threats.  Don’t forget the low-end!