Because cooking really is simple. Our ancestors have been cooking food for many, many thousands of years; it's easier for us to digest many foods if they're cooked. Over thousands of years, we've discovered all sorts of "stuff" about adding flavours, or medicinal qualities to our food (garlic is an incredible antibiotic, honey really is good for sore throats etc), and of course now we know more about how important it is to cook fowl properly (and how much of that has to do with how we raise fowl these days?), but cooking in itself is something our most primitive ancestors did.
It is my personal opinion that most of the dietary restrictions in the Bible were health-based - eg, pig meat (in those days) had/has (?) a high chance of carrying various parasites, including worms, which would transfer to humans if the meat wasn't properly cooked through, ergo Jews don't eat pigmeat. Seafood is notorious for causing tummy upsets if not managed properly - and how exactly does a desert-dwelling tribe keep shellfish good to eat?
(There's a bit of me that wonders whether pig meat tastes too much like long-pig [human] meat, and it was the start of weaning folk off cannibalism?)
OK, I'm not saying an utter novice could turn out a perfect soufflee (sp?) but honestly, anyone with a bit of nous can produce a tasty stew.
It's not rocket-science, it's fun, and it's easy. Honest.