It wasn't needed because the STS wing area achieved the goal of not overflying the Soviets after dropping off a military satellite (once-around mission out of V

It wasn't needed because the STS wing area achieved the goal of not overflying the Soviets after dropping off a military satellite (once-around mission out of Vandenberg SLC-6), and the US had many politically friendly potential landing areas, while USSR did not. Catering to NRO and USAF wartime requirements doomed the STS to cost overruns. Sticking with Faget's designs and the NASA requirements may have salvaged the program's cost goals, but I'm no expert.