I think it makes sense to compare relative to body weight, but even more sense to compare to lean body weight. A slight improvement on this is to base everything on height, perhaps height squared to be more precise. So I would propose the following as a new standard. The great thing about standards, there are so many to choose from. Also, the following is for total weight on feet, skin out, not including body weight. Arguably you could include body weight, as a 2 pound pack with 100 pounds of excess body fat is hardly Super-Ultralight. Anyhow...
Super-Ultralight: skin out weight (pounds) = height (feet) x height (feet) x 50% = 12 pounds for 5 foot, 15 pounds for 5'6", 18 pounds for 6 foot tall.
Ultralight: skin out weight (pounds) = height (feet) x height (feet) x 60% = 15 pounds for 5 foot, 18 pounds for 5'6", 22 pounds for 6 foot tall.
Light: skin out weight (pounds) = height (feet) x height (feet) x 80% = 20 pounds for 5 foot, 24 pounds for 5'6", 28 pounds for 6 foot tall.
Norm: skin out weight (pounds) = height (feet) x height (feet) x 100% = 25 pounds for 5 foot, 30 pounds for 5'6", 36 pounds for 6 foot tall.
Heavy: skin out weight (pounds) = height (feet) x height (feet) x 120% = 30 pounds for 5 foot, 36 pounds for 5'6", 43 pounds for 6 foot tall.
SuperHeavy: skin out weight (pounds) = height (feet) x height (feet) x 150% = 37 pounds for 5 foot, 45 pounds for 5'6", 54 pounds for 6 foot tall.