I wouldn't be surprised if there's less passion for the cars themselves, and suspect that they're increasingly thought of less as a significant element of one's identity and more as a simple appliance.
There's probably some element of both in there. Young people get to pick whether they want a white iPhone or black iPhone and customize it with a case of some sort that showcases their identity. Similarly, you can customize your Scion xB the same way.
And similarly, you might plan on ditching both appliances for an upgrade in 2-5 years when you're ready for the next model with new bells, whistles and an ever-sleeker design.