You use big words... lol Thats our reallity tho. No-till farming practices coupled with better fertilizer/chemical plans and seed genetics allows for higher yields in those otherwise marginal areas and last year guys did really good considering the mess they have been in. CRP is still coming out to be farmed as soon as the contract is done. But really if you want an answer get a hold of your local District Conservationist from the NRCS and pose the question to them. I am sure they have other reasons why. It boils down to money.
I have yet to be able to confirm wide scale withdrawals, or an ysignificant amount of money being left on the table. USDA web sites offer no substantiation (in fact, suggest the contrary) so I called USDA this AM and asked about it. It was a mystery to them, not a problem on their radar - but of course I just talked to one guy in DC, so no hard proof there. Kind of like asking your FaceBook friends - no science behind it.
FWIW, not clear to me how no-till (with its increased chemical requirements) or state of the art genetically engineered seeds would change the economic balance. Tons of chemicals and high tech seeds cost more; more input coupled with more output would equal a net zero gain for the most part. Furthermore - watch oil prices. Rocketing upward. That will translate very shortly into much higher chemical prices, and that won't favor working marginal soils by any means.
What I thought you'd overlook in your analysis (OK, that's kind of tricky - but you one upped me by not dong one!) was the one factor everyone seems to miss: risk. Or more precisely, lack thereof. Farming is, was and likely always will be a highly risky business. Everything from weather, to pestilence, to pandemics, to strained international relations, to God knows what all act to make tilling the soil a real crap shoot, each and every year. Yes - I may make double the net profit one year by planting soybeans, corn, wheat, alfalfa etc --- but I may also lose every dime of fuel, seed, chemical, equipment purchase or rental and capital cost - along with every labor hour of input. And often do.
With CRP that government check just keeps on coming in, no matter what. No risk, no worry, no labor. In business terms - that is an excellent deal. They are always welcome to send me more OPM (other people's money) if they wish, but I'm all in at current rates.