One thing that makes AA's program great, is that it is simple to understand. There are three different ways to qualify for elite status. Most business travelers don't want to spend a ton of time figuring out how a FF program works. If you move to a revenue based system, it does make the program more complex.

It is simple to add up segments or miles. When you have to multiply a factor by the miles based on ticket class it takes more time and effort. As it is, most loyatly programs have too many rules and exceptions. AAdvantage has a competitive advantage (for me) due to it's simplicity.