Alfred,
All fair points for the type of the war the USAF wants to fight, but utterly unlike the wars we've spent the last 20 years fighting. For near peer wars surely providing a favourable air situation for the likes of the A10 to operate in is why we've spunked Billions on Gen 4.5 and Gen 5 fighters? If you're arguing that they can't then why have we bothered?
For some roles speed is a disadvantage - payload/loiter and the ability to take lumps and stay in the fight is more important.