They caught on because they did such a wonderful job of exploiting human nature. From his own experience with green stamps, Mr. Plaskett knew that collecting stickers or points could feel like an accomplishment in itself. So, American Airlines deliberately handed out thousands of them at once, because "10,000 miles" sounded a lot more impressive than "6 flight segments."
Just as they were intended to do, the programs delayed the march of low-fare carriers. One study done in the 1990's found that business travelers taking a 1,000-mile trip would pay an extra $170 on average to fly on the airline with their frequent-flier program.
Frequent-flier programs are not about to disappear, because no airline can afford to abandon them unilaterally. But compared with Mr. Crandall's original goal — to keep airline seats from becoming a commodity — the frequent-flier mile is looking pretty old and tired for a 25-year-old.