Protein is in meat. And meat is expensive.
Protein is an important part of a cat's diet, but it is also usually the most expensive ingredient in your cat food. So many cat food makers skimp on protein to cut down on costs.
So basically, the more protein, the better quality the meal.
A savvy cat owner should look to find the most protein for the best value. In the below table we break down the amount of protein in various cat foods, the price, and then the protein per dollar so you can work out the value.