I think it has been pointed out in the past, the rocket gets back to operational status in less time than it would take to switch rockets. A good data point would be to look how long Delta IV was down when they cracked the pad with a LOX leak.
They most likely could rebuild the pad in less time than it would take switch rockets.
And that was kind of my point to Robotbeat's argument about assured access with redundancy. I hadn't even thought of the issues of taking payloads designed to fly one one EELV and then having to switch them to the other, and the difficulties in that.
But this isn't the height of the cold war any more. How critical is it for USAF/DoD payloads to go up on time in the event of a major problem like a pad being damaged and needing repaired. I don't know if there's many needs to loft a new spy satellite up ASAP to monitor some movement of Soviet warhead from one place to another. At this point I think they are just replacing their existing network of survellence satellites as they get near the end of their service life. How often is it that that replacement couldn't be delayed a year in such a circumstance?
I don't know myself, I'm just assuming that 6 months or a year delay in a payload while a pad was repaired, even a secret national security payload, isn't the big deal it would perahps have been a few decades ago.
And thus, is having two pads on each coast operational all that necessary for assured space access?
If so, I'd think it'd be more important to have two pads on each coast that can launch the same LV, so that if one was damaged, they critical payload could be moved to the other and launched on the same LV and integrated in the same way. Something that's not currently possible.
Something like a combination of LC-39 and LC-41, where there's a single VIF and then two pads that the mobile launcher could go out to either in case one was damaged.
Or LC-17 with two towers on two pads.
Or adding another MSS and tower to LC-37. The Delta's could be integrated in the same HIF, but then go out to either pad.
I think that would be better for assured access to guard against an inturruption in flights due to a a damaged pad, and obivously that hasn't been seen as important enough to do yet by USAF.
Having two redundant LV's as a hedge against one being grounded for assured access to space I think more applies to a new LV that could have some design flaw that would cause it to be grounded and fixed...which could be a long and difficult process depending on the problem. I think that was part of the reason USAF kept both EELV's while retiring most of their existing ELV's. But I think it's save to say after 10 years that neither Delta nor Atlas has any such design flaws that would require any long term grounding. So I don't know that that conern is still applicable today.