S&H Green Stamps in the 50's were based on $ spent and Americans were fascinated and devoted. Americans are now clearly devoted to frequent flyer credit cards where rewards also are based on $ spent.

In the early days of commercial air, being a "***"-miler meant a lot and it carried a lot of prestige.

But since AA introduced the mile program it's become an institution which captivated Americans (as this site demonstrates) and which people love to figure out ways to "game". It's fun.

Also it requires brand loyalty which marketing is all about.

The new Southwest program is rational but boring. It's just giving back a certain %. Folks fly Southwest (or AirTran) because they're cheap. If they can fly a "brand name" carrier for the same or close price they will. As Southwest's prices go up they'll regret not having established brand loyalty through a popular FF program.