The original B-1A was built for unusual (Nuclear) missions of high-altitude high-speed penetration. Before the B-1A became the IOC, the Soviets had built air defenses that could topple it. (Advanced SA-2 systems and SA-5 systems as well as MiG-25) Thus convention canx the B-1A.
Then, to avoid a huge loss in development and acquisition spending, the Regan administration, under great USAF pressure, brought it back and repackaged it as a non-nuclear B-1B with low-level supersonic capability and a non-nuclear mission, surrounding nuclear deals. time speaks. So it’s not “downgraded”, just changed the task. No matter how you look at it, it’s bad for B-ONE.