Someone out there surely knows more about this than I do, but AFAIK frequent flyer miles that can be redeemed for awards generate a balance sheet liability. I don't think upgrades do. Because UA is still trying to generate cash flow, trading cash for liabilities (albeit much lower liabilities than the cash geneated) can make sense. At the same time, these incentive programs and MP liberalizations generate good will that retain flyers and, perhaps, attract more from airlines cutting back. Seems like sound decision-making.