The issue with the idea of selling +7 (for example) foods in the shop is the incredible difference in power between a +10 stat gain and a +7 stat gain for most stats. +7 foods would be fine for, say, int and vit, and fine for casters for dex, but it would do very strange things to physical damage dealer's character builds, as +7 is not enough to reach from one offensive breakpoint to the next.
I understand the desire to make the in game system for food useful, but I feel like not adding the regular foods to the Kafra Shop would be shooting yourselves in the feet, as it were, due to their high demand and low controversy.
Yep, the original +10 kafra-shop will generate more money.
There is two way I see that is good for this and make both kafra-shop and cook-food useful.
1. Keep +10 Kafra foods and make the cooking food stack with the kafra-food.
This will make the cooking food very valuable as it stacks with the kafra food and making a huge demand because if you want to be the strongest you will hunt for these.
2. Making Cooking-food ingredients much more simpler as my suggestions above.
I believe the main goal is to satisfy players while still generate sustained income from the kafra-food. Keeping the +10 foods as is good as it's always been there and have been a sustain source.
The only change should be made is with the cooking system/cooked food, not the kafra food.