I had an accident two years ago and couldn't walk for six months or bend my legs for another six. I know that without my big 05 Expedition I wouldn't have been able to get around on my own without the extra room these vehicles provide.
As for your mileage, that is about what you can expect for that one ton. My expy with 5.4 can get 17 on the highway with the better geared rear end, but my wife's lead foot punching it whenever she drives brings the usual average down to 12.
If you need a one ton for hauling, towing, etc, then keep it. If you want a truck for size, comfort, but also mileage and not a lot of money, then maybe look around for a 97 to 02 F-150 extended cab with a 4.2l V6. They can get up to 20 mpg and are reasonable in the price. If you traded for it you could get cash back between it and your one ton.