I got a 4X4 because it came with the model I wanted. Couldn't really see any practical benefit, and in the first year I never used it.
But on two occasions this year, once in Atlanta at Stone Mountain and once in Indiana at a state campground, I was given a spot that required me to back up, uphill, on gravel to hook up to my 5th wheel trailer. Both times, I started to dig holes in 2-wheel, but when put into 4-wheel, it backed up perfectly with no spinning. Those big truck tires can dig quite a hole in a single second!
Anyway, glad I have a 4X4, but if faced with the choice vs the expense, I'm not sure what I'd do.