They aren’t stealthy and don’t cost $1 billion each and require 2 decades of development time. Therefore, the Air Force has no interest in them.
Heh. True.
Incidentally Lockheed and others have been kicking around plans like this for at least 20 years, probably much more. They can launch them out of cargo planes like C-130s or C-5s too... but again, not sexy enough for the jet jockeys at the top.