Thank you for making my point. If the aging F-15 suits a particular mission without stealth just fine, then it would be no issue to run the F-22 in a less stealthy mode. However, if the mission entails deep penetration into IADS, well only the F-22 can do that currently.
However, you are wrong to say the F-22 has less firepower than the F-15. The maximum payload of the F-15E Strike Eagle is 24,000 lbs. The F-22 can carry 20,000 lbs externally and 2,000 lbs of bombs internally plus hold four missiles.
I guess its a question of mission again. What purpose does this plane serve? Is it a stealth interceptor? Is it a light bomber? Is it to kill heavy bombers?
Why not all of the above? The F-15 was designed to be an air supremacy fighter. Period. But what the USAF found with the Eagle is that it was such a good design, that it could be adapted to do other roles. Hence the Strike Eagle introduced 12 years after the original Eagle. Now we have the Raptor, and it is superior to the Eagle in every way. There is no reason there couldn't be a "Strike Raptor."
As far as I can tell, its real purpose is to suck money out of the pockets of taxpayers and put it into the pockets of Lockheed and Boeing.
That could be said about any weapons system. I suppose that when the F-15 was being developed, you argued that the F-4 could do everything the F-15 could do, and do it cheaper. And at that point, the F-4 could carry 18,000 lbs of bombs and the F-15 could not.
Sure there is. Cost per plane, and availability.
A hangar queen cannot meet the needs of the nation, and we can't afford to buy twice the number of planes to account for that because they are so damn expensive to beging with.