Diet Ability overhaul + Metabolism Abilities
One of the main gripes I see people having with the current diet abilities is they're just less interesting and unique than the old diet system, where different dinos had different things they could eat (struthi bugs and berries, ceratopsids nuts roots and shellfish etc). I think repurposing the current diet abilities into "metabolism" abilities and instead turning the diet abilities into a "pick what you eat system" would be far more interesting.
The current diet abilities would be *just* metabolism. They would be entirely unrelated to what you can eat, and instead simply alter your food/water drain and stamina. Diet "abilities" would be rehauled into unlocking certain additional food types. EG by default a herbi can eat bushes, but can choose to also eat lychees, or acorns etc. Each food type comes with a small positive and negative effect to certain stats (very minor, ~5%), eg amanita = better health regen, worse health. See image for more in-depth details!