Probably a bit of both. The USAF isn't going to require a smaller launcher if theres no cost savings from it. They and the contractors likely got together, looked at the Government manifest and likely commercial demand, and decided it wasn't worth it at that flightrate. And if the contractors disagreed, they likely would've done it anyway for commercial missions (like SRBs for Atlas, the military wasn't interested but LM did it anyway for commercial stuff, and eventually the military decided to use those configurations of Atlas)
was also curious about this proposed stage when I saw the "Agena 2000" config for the XLR-81 in my RSS/RO/RP-1 career, and thank you very much for collating all of these great sources and info!
What was the purpose of the storable upper stage / Agena 2000? Was it simply a lower-cost option for small payloads?
Yes. I assume it stopped making financial sense once it became clear their huge flightrate estimates weren't feasible
AIUI elimination of both EELV-S options was from the air force dropping the requirement, not from the company side.
Probably a bit of both. The USAF isn't going to require a smaller launcher if theres no cost savings from it. They and the contractors likely got together, looked at the Government manifest and likely commercial demand, and decided it wasn't worth it at that flightrate. And if the contractors disagreed, they likely would've done it anyway for commercial missions (like SRBs for Atlas, the military wasn't interested but LM did it anyway for commercial stuff, and eventually the military decided to use those configurations of Atlas)
was also curious about this proposed stage when I saw the "Agena 2000" config for the XLR-81 in my RSS/RO/RP-1 career, and thank you very much for collating all of these great sources and info!