I'll confess, one of the more surprising results of my recent research into Agile development in practice is the large number of motives to go Agile. From eliminating useless documentation to shortening development cycles to making the schedule more predictable, there were as many different reasons for Agile as people I interviewed.
Perhaps that's part of the success story of Agile: partly by design, partly by historical accident, the Agile movement addressed many different needs. In this way, Agile is a lot like the Protestant Reformation. Remember junior high school history class, when we heard that Luther's protest conveniently occurred just when secular princes were looking for ways to gain independence from Rome? The Agile movement arrived when more was happening in the technology industry than just the disgust of developers with schedules in which no one believed, or projects that didn't deliver what the customer wanted.