It's not the Iranian aircraft, per se. It's the advanced SAM systems that the Russians have been feeding them.
The F-22 (and its reputation) keeps OPFOR Air Forces on the tarmac. Remember how the Iraqis would flee from (and return to the airfield) if they were painted by F-14 radars?
Sure, Ahkmed and his buds will not have much beyond a King Air, but 'Lin Chau' in SE Asia, and Hugo Chavez Jr in S. America will.
Not all threats are terrorist, and the ability to deter/defeat the enemy so that we have air SUPREMACY gives us freedom to prosecute our battle plan. If we control the order of battle, we win. (um, as long as our politicians let us ...)
Sure, there's still a BIG role for other aircraft types -- manned and unmanned, including the B-52 up through F-15Es and Super Hornets and Falcons. The F-22 and soon the JSF will give us an extra edge that we really need.
Besides, a great deal of air-to-mud is gonna go RPV anyway. There, I threw in THAT thread-hijacker ;-p