Does anyone know if the roof rails can serve any functional purpose other than an aesthetic one? There isn't any space between the roof rails and the car, so it looks like you have to pay the additional $290 for the cross bars on top of the $370 for the roof rails in order for them to work. I don't understand why Infiniti offers this as two separate options. I use the roof rails on my current SUV only once a year for my Christmas tree, and I'm wondering if it's worth getting on the JX...