I don’t understand the need for a heavy bomber. Instead of paying 5 to 10 times the price of an F-22, build the extra F-22s instead. You end up with more flexibility and more bomb load.
Range and logisitics/timing. If you had 10 F-22s, you'd have to schedule 10 refuelings each time the birds needed a drink, and they'd need one more times than a big bomber would. You'd spend a lot of time hooking up to and unhooking from the tankers. The booom probably wouldn't work, having been designed and built by Frenchmen, or French nationals anyway, possible of the Islamic persuasion.