Them B-52s have had "Frame-Off" restorations several times already.  The air-frames are old in design, but much of the metal is fairly new, with some having been replaced by composites.
And the lion's share of the military budget has been going to our incessant proxy wars in the Middle East.  Our equipment is on about it's third complete rebuild.  Our most effective weapon systems are to few, to complex, too expensive, and scattered all over the world in penny-packets.
It took months to build up sufficient force for the Iraq wars.  We are strong nowhere, and vulnerable everywhere.
The next big war could easily go nuclear, and a priority on civil defense would be more immediately valuable to our citizens, than any number of tanks and aircraft.
We certainly need a force in being, as a deterrent, but we also need that force to be quickly expandable, without needing specialists to operate complex systems.  Spare parts in the field are a must.  FedEx and UPS works only for small conflicts.