I really wish they'd substitute an SSL when the PPCs aren't available. All I care about are comfy seats facing a big window, and I have a feeling that many passengers feel the same way.
While I understand your logic & reasoning, and don't disagree with it, the reason that CCC's is kept on standby for the PPC's is that the CCC can still provide meal service. The Sightseer Lounge cannot do that.
And Amtrak needs that to ease the load on the dining car; not to mention that the revenue credited to the PPC program from those meals being served is what helps to keep those cars in service. Take away that revenue and the PPC's are finished. Amtrak won't run them at all without that extra revenue helping to justify the huge costs to run those cars.
I wish they'd add an extra SSL as a "First Class Lounge" to each of the major scenic western trains, that would be amazing.
Sadly, Amtrak simply doesn't have enough cars to do that.
However, if ridership continues to grow and assuming that Amtrak can find funding for new Superliner cars, it is something that Amtrak should consider. Especially since they could do much like they do on the Auto Train, and leave one half of the car tables. Those tables could then be utilized as overflow seating for the dining car, allowing Amtrak to feed more people and add an extra sleeper or two to each train's consist and therefore carry more passengers.