I have an '06 and change the filter every other oil change; 10,000 miles. It's as black as sin when I take the old one out. Since I have a plastic tank, I assume the filth is from the fuel.
I imagine it's as important to change it on the newer trucks as well as it was on the older trucks. But $63 each and there are TWO??!! Yeow!! That hurts.
I'd follow the owner manual for recommended fuel filter changes. I'd also look into installing an aftermarket filter that doesn't cost as much to change and ahead of the factory filters in order to extend their lives.