Jet-A on contract isn't any $6.70 per gallon, at least not yet.
I’ve seen what might be called “spot” price pushing $7.00 a gallon quoted at certain FBOs at certain airports; I’ve got no idea what airlines actually pay.
Hopefully much less.
The point remains - pulling 500 pounds out of the airplane basic structure will either save several hundred dollars a day in fuel costs per airplane, or allow carrying 500 pounds of freight.