Originally Posted by eamus
Interesting that AFAIK the only US airline that offered redemption on the basis that if there's an empty seat it's yours can no longer sustain that model. Presumably they looked at increasing the redemption cost in credits (which would have the same effect of reducing the overall number of award seats redeemed) and decided that controlling the inventory would earn them more in paying customers.
NZ Airpoints now does this, but with a twist. Only valid on NZ metal and the cost in airpoints is whatever the fare is for that seat (there are also other discounted award seats that are capacity controlled). So consumer gets more award availability, but may be at a higher cost.