Basically the average age of a Toyota owner is pretty up there. IIRC, only Buick's average age owner is higher. Toyota wanted to lower the average age of its owners, like rival Honda. The reason being is start them off young into the Toyota brand, and eventually, they'll move up to Lexus. Toyota tried to grab younger buyers with the Echo, but it attracted even older folks. So it was decided to create a new hip brand, Scion, for younger buyers, which will eventually move to Toyota and then Lexus.

There's an interesting strategy for Scion too. Scion is on pure pricing, each dealer sets its own price for Scion models. There's no haggling or negotiating on Scions, two different people will pay the same price for the same car from the same dealer. (IMO, Scion could've done better like Saturn and make the price the same across all dealers.) It's under the expectation that young buyers don't have experience in negotiating a "good deal" on a new car.