Then why bother with very expensive strategic bombers when unmanned short-range missiles, medium-range missiles and ICBMs plus piloted or unmanned strike aircraft can do the same job in almost all military situations for far less cost?
Because the missions needed can not be addressed by the systems you mention.
First of all, remember that each of these bombers is not only a nuclear bomber. They also fulfill a conventional strike role.
So just eliminate ICBMs altogether. Those are only nuclear.
Short range? Strategic bombers are long range. So any mission more than around 200 miles is no longer capable of being fulfilled by those weapons.
Unmanned strike aircraft, not likely. To vulnerable, to lightly armed. Great if you want to go after an SUV with a known target, of no real use on a battlefield.
Same with strike aircraft. They generally have a rather limited air to mud capability, mostly because of the amount of ordinance they carry. They also have an endurance issue. Most are only good for maybe 4 hours or so on station, then they have to return to base. Strategic bombers do not have this issue, and can literally linger over a battlespace for a day waiting for a call.
When I was deployed, we got to know the regular times that the B-1s and B-52s would take off to do their missions. Generally it was 4 times a day. 2 daytime launches, one going to Iraq, the other to Afghanistan. Then at night, the same thing. And the procedure was that these aircraft would hang out in locations near a battle (or expected battle), and respond if called.
And excuse me, "at far less cost"? What planet are you living on?
A single BUFF can carry 70,000 pounds of bombs.
The F-15E can carry 2,000 pounds of bombs.
So are you really trying to claim that flying a fleet of 35 F-15s is a lower cost than sending a single B-52?
And let's take this a bit farther. The only UCAV that carries bombs is the upgraded Predator known as the MQ-1C Grey Eagle. It carries 4 2 pound bombs, for a total of 8 pounds of explosives. Is it really cheaper to send 8,750 drones to do the job of a single B-52?
That is 8,750 drones, and 8,750 pilots. At a cost of $21.5 million each. You just spent over $188 billion, to replace a $14 million dollar aircraft. Not counting the fuel, personnel to maintain and operate the aircraft, and all the other costs.
So please tell us again how drones doing the same mission is less expensive.