I don't imagine that it would up well as a daily beater in SOCAL traffic...but that's not what it's for. I think the idea is that you can drive it to the airport, fly to your destination, and then not have to rent a car.

Fundamentally nothing wrong with this idea...you simply have to be willing to give up some performance in both modes in exchange for flexibility. If you want performance and capacity for a family of five, buy a light twin and rent an Expedition when you get there.